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Zaps – Internal

by Ira @ 12:15 pm on August 24, 2011.

ROM / RAM / PORTS / CALLS / TOKENS (The inside stuff)

Menu

CPU/ROM

	ROM Addresses
	ROM Calls
	ROM RST Vectors
	ROM Routines (I/O & Misc.)
	ROM Routines (Integer Math)
	Entry Points to Level II BASIC ROM
	Z-80 Instruction Set
	Undocumented Z-80 Opcodes

Cassette

	System Tape Format
	EDAS Tape Format
	BASIC Tape Format
	Cassette Volume Settings

I/O

	Port Addresses (Model I)
	Port Addresses (Model III)
	Memory Mapped I/O Devices
	Port Addresses (Model III/IV)
	Model III RS-232 Ports
	Model III WD1793 Disk Controller Ports
	Radio Shack 5/15 Meg HD Port Assignments
	UART Bits
	Model 1/3 TRS-80 Keyboard PEEK Table
	Model 4 TRS-80 Keyboard PEEK Table
	Directly Access Model 4 Video
	Model 4P Modem Controls
	Model 4 Graphics Board – Undocumented Ports
	Model 4 Video Locations

Other

	DOS Routines
	Level II/DOS RAM Map
	Disk Basic Command Vectors
	Disk Speed-Up Chart
	RAM Addresses
	Tokenized BASIC
	Pokes and Peeks
	Vidtex Escape Sequences
	Model 4P Boot Mode Select
	Programming the Model 4 Function Keys
	Changing the Model 4 Speed (4MHZ Model 3/2MHZ Model 4)
	Controlling the Model 4 Sound Card
	Interesting Model 4 BASIC Commands

RAM Addresses

The following keys for DOSes apply:
	T1 – Model 1 TRSDOS	T3 – Model 3 TRSDOS
	N1 – Model 1 NEWDOS	N3 – Model 3 NEWDOS
	L1 – Model 1 LDOS	L3 – Model 3 LDOS
	M1 – Model 1 MULTIDOS	M3 – Model 3 MULTIDOS
	D1 – Model 1 DOSPLUS	D3 – Model 3 DOSPLUS
	All – All DOSes, Model I and Model III.

Hex	Decimal	Description
3C00	15360	This is the beginning of video ram or VIDRAM. It ends at 3FFFH or 16383.
	16333-16334	End of BASIC Program Pointer (LSB,MSB)
4000	16384	RST 08 Compare value pointed to by HL to that immediately following RST instruction.
4003	16387	RST 10 Examine next symbol pointed to by HL.
4006	16390	RST 18 Compare DE and HL.
4009	16393	RST 20 Test the type of current varible.
400C	16396	RST 28 3 byte break key vector (cass. Basic & TRSDOS 1.3) and normal Dos function call.
400F	16399	RST 30 Reserved for Dos – normally for invoking Debug.
4012	16402	RST 38 Maskable interupt vector.
4015	16405	Beggining of Keyboard DCB. One byte device type. = 1
4016-4017	16406-16407	Two byte keyboard driver vector. To Disable The Keyboard:
		N1=PEEK(16406) (MOD 1) N2=PEEK(16407) POKE16406,154 POKE16407, 10 THESE FOUR STEPS DISABLE THE KEYBOARD. TO RE-ENABLE IT: POKE 16406,N1 POKE 16407,N2
4018	16408	Right SHIFT toggle.
4019	16409	Caps lock switch (Not 0 = Caps only)
401A	16410	Cursor blink count
401B	16411	Cursor blink status. (0=blinks)
401C	16412	Cursor blink switch (0 = blink)
401D	16413	Beggining of Video DCB. One byte device type. = 7.
401E	16414	Two byte video driver vector.
4020	16416	Two byte cursor position.
4022	16418	0 = Cursor on, Not 0 = character replaced by cursor.
4023	16419	Cursor Character (in ascii).
4024	16420	FLAG : 0 = Space compression; Not 0 = special character.
4025	16421	Beggining of Printer DCB. One byte device type. = 6.
4026	16422	Two byte printer driver vector.
4028	16424	Maximum lines printed per page +1. Default = 67.
4029	16425	Number of lines printed +1.
402A	16426	Character counter + 1.
402B	16427	Line printer maximum line length less two.
402C	16428	“R”
402D	16429	Return to Dos exit. (Disk systems only).
4030	16432	For all doses except TRSDOS, is abnormal return to DOS ready.
4036	16438	Keyboard buffer (7 bytes).
403D	16445	Cassette port and print size flag (bit 3) copy (For Model 3, see 4210). L3: location of routine to add task to interupt chain.
403E	16446	For Model I DOSPLUS, hold DOS version in DCB format.
4040	16448	For L1 & M1, 25 ms heartbeat counter. For L3, used to remove task from interrupt chain.
4041	16449	Beginning of Time and Date bytes. (seconds, min., hours, year, day, month) Ends at 4046H or 16454. L1, D1, and M1
4043	16451	L3, change address of interupt task.
4044	16452	L1, D1, & M1. Contains date in binary format.
4046	16454	L3. Remove task from interupt chain.
4047	16455	L1. Current day in coded form.
4049	16457	For the Model III disk is non maskable interupt vector, for Model I disk is highest available memory location (Model III = 4411H)
404B	16459	L1. Contains image of interrupt latch.
408E	16526	Address of USR routine (two bytes)
4099	16537	INKEY$ storage. Most recent keyboard character.
409A	16538	Error code is at this address (for BASIC only)
409C	16540	OUTSEL. On Model I, is a one byte output device flag. -1 (or 129) for cass, 0 for video, 1 for printer.
40A0	16544	Clear address pointer. Beggining of CLEARed area for string variable storage
40A0	16544	LSB of Lower Limit for String Variable Storage Space
40A1	16545	MSB of Lower Limit for String Variable Storage Space
40A2-40A3	16546-16547	Last executed line number/Program Line Counter (LSB-MSB).
40A4-40A5	16548-16549	Pointer to beggining of Basic program (LSB-MSB).
40A6	16550	Cursor’s current column number.
40A7	16551	Input buffer pointer.
40A9	16553	???.
40AA	16554	3 byte random seed number.
40AB	16555	This byte is changed by RANDOM.
40AF	16559	SAFLAG. Contains typeflag of software accumulator.
40B1-40B2	16561-16562	Two byte End (Upper Limit) of String Storage – LSB & MSB.
40B1-40B2	16561-16562	Two byte MEMTOP (for BASIC) – LSB & MSB.
40D3	16585	Saves length ASCII representation of binary integer.
40D4	16586	Two byte address. Points to buffer where ASCII decimal representation written.
40D6	16598	String pointer. Keeps track within CLEARed area as to where last string data was put.
40D8	16600-16601	Two byte location of where Basic is currently reading program/Present BYTE Counter (LSB & MSB).
40DF	16607-16608	Default entry point for SYSTEM tapes (LSB & MSB).
40E1	16609	Auto flag.
40E2	16610	Current auto line number.
40E4	16612	Auto increment.
40E6	16614	Pointer to terminator (end of line 00H byte or “:”) of the last executed Basic statement is at this address.
40E8	16616	Beggining of Basic’s stack.
40EA	16618	Two byte address. Contains line number with error.
40EC	16621	Two byte address. “.” line number.
40EE	16622	Pointer to I/O buffer.
40F0	16624	Pointer to line of BASIC error handling.
40F2	16626	Error flag.
40F5	16629	Current line number.
40F9	16633	End of basic program/ start of simple variable list pointer.
40FB	16635	Start of arrays variables pointer.
40FD	16637-16638	End of arrays variables/ start of free memory pointer (LSB,MSB).
40FF	16639-16640	Two byte address. Current location of Basic’s DATA pointer (LSB,MSB).
4101	16641	Beginning of variable type table.
411A	16666	End of variable type table.
411B	16667	Trace flag.
411D	16669	First byte of SA.
4124	16673	Last byte of SA.
4127	16679	First byte of SA1.
412E	16686	Last byte of SA1.
4152	16722	CVI 3 byte vector.
4155	16725	FN 3 byte vector.
4158	16728	CVS 3 byte vector.
415B	16731	DEF 3 byte vector.
415E	16734	CVD 3 byte vector.
4161	16737	EOF 3 byte vector.
4164	16740	LOC 3 byte vector.
4167	16743	LOF 3 byte vector.
416A	16746	MKI$ 3 byte vector.
416D	16749	MKS$ 3 byte vector.
4170	16752	MKD$ 3 byte vector.
4173	16755	CMD 3 byte vector.
4179	16761	OPEN 3 byte vector.
417C	16764	FIELD 3 byte vector.
417F	16767	GET 3 byte vector.
4182	16770	PUT 3 byte vector.
4185	16773	CLOSE 3 byte vector.
4188	16776	LOAD 3 byte vector.
418B	16779	MERGE 3 byte vector.
418E	16782	NAME 3 byte vector.
4191	16785	KILL 3 byte vector.
4194	16788	& function 3 byte vector.
4197	16791	LSET 3 byte vector.
419A	16794	RSET 3 byte vector.
419D	16797	INSTR 3 byte vector.
41A0	16800	SAVE 3 byte vector.
41A3	16803	LINE 3 byte vector.
41A6	16806	ERROR Error processing jumps to this three byte vector. In cassette Basic it contains RET instruction, in Disk Basic, contains a jump (through RST) to long error message
41A9	16809	USR 3 byter vector.
41AC	16812	Ready prompt
41AF	16815	Called from 0368H to input line from keyboard to I/O buffer.
41B2	16818	Called from 1AA1H immediately after BASIC line is tokenized. HL points to tokenized line.
41B5	16821	Called from 1AECH immediately after BASIC’s table of prg lines are updated. After call to 41B5H, BASIC calls CLEAR routine at 1B5DH then calls this dos exit from 1AF2H
41BB	16827	Called from 1B8CH and 1DB0H during NEW and END processing to allow Disk Basic to close any open files.
41BE	16830	PRINT# processing called from 2174H
41C1	16833	Byte output to any device. Called from 032CH so output to disk can be handled as to other devices.
41C4	16836	ROM KB scan (0358H) calls this exit. BASIC processes INKEY$ here and also after each command when system searches for break or shift @.
41C7	16839	Called from 1EA6H when RUN is followed by filename or line number
41CA	16842	Related to 41BEH above. Called at beggining of print processing from 206FH to check for possible disk output.
41CD	16845	Called from 20C6H. Call is made during print processing after number is in ASCII and just before printing. Could be used for Hex and Binary printing.
41D0	16848	Called from 2103H (from PRINT routine after code that send CR.) Could be used for screen wrap-around.
41D3	16851	Called from 2108H and 2141H. First is for printing with comma tabs, second is for printing with TAB statement. Could be used to increase length of original tabs from 63 or 127 up to 255.
41D6	16854	INPUT# processing. Called from 219EH to check for INPUT# command and to provide input from disk.
41D9	16857	Left side of MID$ processing. Only DOS exit BASIC jumps to instead of calls. Used to allow MID$ on left side of equals sign.
41DC	16860	Variables assignment. During processing of READ & INPUT statements, after computer recieves value and before assigned to variable, BASIC calls this exit from 222DH.
41DF	16863	Called twice from BASIC: From 2278H after BASIC assigns input value to variable and just before BASIC searches for extra data that will generate “Extra ignored” message, and from 2B44H from the midst of list processing. Could be used to alter list command.
41E2	16866	SYSTEM command processing. Called from 02B2 just before “*?” prompt. A system tape will automatically start if a jump to its starting address is placed here. Keep in mind this is a 3 byte location. The first byte should be C3H which is the code for “JP” and should be followed by the starting address of your program.
41E8	16872	$RSRCV input buffer (1 byte)
41F0	16880	$RSTX output buffer (1 byte)
41F8	16888	$RSINIT baud rate code. TX code = most sig. nibble, RCV code = least sig. nib.
41F9	16889	$RSINIT parity/word/length stop-bit code
41FA	16890	$RSINIT wait switch (0 = wait, Not 0 = wait)
4209	16905	L3. Checks for drive and mounted disk.
4210	16912	Various controls: See port EC
4211	16913	Cassette baud rate switch (0 = 500 baud, Not 0 = 1500 baud)
4214	16916	Video display scroll protect (range = 0 – 7)
4217	16919	Model 3 time. Contains time in binary format.
421A	16922	Model 3 date. Contains date in binary format.
4220	16928	$ROUTE destination device (two bytes)
4222	16930	$ROUTE source device (two bytes)
4225	16933	T3, L3, D3. Dos command buffer.
4288	17032	L3. 33.33 ms heartbeat counter.
428A	17034	L3. Send message to Job Log and CRT.
428D	17037	T3, D3. Find drive and file number for open file. For L3, send message to Job Log.
4290	17040	T3, L3, D3. Copy directory to RAM buffer.
4293	17043	Get file name from directory.
4296	17046	L3. Execute Dos command and return to DOS ready.
4299	17049	T3. Do DOS command and return to DOS ready. L3: returns to caller is @EXIT and @ABORT vectors change to jump to return address.
429C	17052	T3. Do DOS command and return to caller.
42AD	17069	D3. Contains address of break key routine.
4312	17170	D1. Contains address of break key routine (195=Off, 201=On).
4318	17176	T1, L1, D1. DOS command buffer.
4396	17302	L1. Read directory into memory.
4400	17408	L1, D1, D3, N1, N3, M1, M3. Same as 402D: return to DOS ready.
4402	17410	Send text to file or device.
4405	17413	L1, D1, D3, N1, N3, M1, M3. Do DOS command and return to DOS ready.
4409	17417	Display error message on CRT.
440D	17421	L1, L3, D1, D3, N1, N3, M1, M3. Enter Debug.
4410	17424	L1, D1, N1, M1. Add task to interrupt chain.
4411	17425	Address of highest available memory location (Mod III disk only – Mod 1 disk = 4049H)
4413	17427	L1, D1, N1, N3, M1. Remove task from interrupt chain. For D3, add task to interrup chain.
4415	17429	T3 (undocumented) Second copy of high memory address. Copied to 4411H in case of I/O error during DO processing.
4416	17430	L1, M1. Change entry address of task in interrupt chain. D3: Remove task from interrupt chain. N1, N3: Keep drives rotating and reselect current drive.
4417	17431	L3. Contains current day in coded format.
4419	17433	T3, L3. Write disk directory to screen or buffer. N1, N3: Execute DOS command and return to caller.
441C	17436	T3, L1, L3, D1, D3, N1, N3, M1, M3. Move filespec to FCB.
4420	17440	All. Open or create a file.
4424	17444	All. Open existing file.
4428	17448	All. Close a file.
442C	17452	All. Remove file from directory.
4430	17456	All. (undocumented in T1) Load file (m.l. program) into memory.
4433	17459	All. (undocumented in T1) Load and run m.l. program.
4436	17462	All. Read logical record into memory.
4439	17465	All. Write logical record to disk.
443C	17468	All. Write record and verify.
443F	17471	T3, L1, L3, D1, D3, N1, N3, M1, M3. Point to first record in file.
4442	17474	All. Position file to specified record.
4445	17477	T3, L1, L3, D1, D3, N1, N3, M1, M3. Backspace file one record.
4448	17480	T3, L1, L3, D1, D3, N1, N3, M1, M3. Position to end of file.
444B	17483	T3, L3, D3, M3. Add extension to filespec in FCB (see also 4473). L1: Check for end of file. D1: Multiply 16 bit by 8 bit integer. N1, N3: Allocate disk space to file.
444E	17486	T3, L3, D3. Multiply 16 bit by 8 bit integer. L1: Update directory with current record as end of file. D1: Divide 16 bit by 8 bit integer. N1, N3: Position file to specified byte record.
4451	17489	T3, L3, D3. Divide 16 bit by 8 bit integer. D1: Check for end of file. N1, N3: Update directory with record as end of file.
4454	17492	L1 Read current sector. L3, D3, M3: Parse parameters in command line. D1: Find drive and file number of a file.
4457	17495	L1 Rewrite current sector. D3: Check for end of file. D1: Read directory to user buffer.
4458	17496	L3. Check for end of file.
445A	17498	L1. Calculate current logical record number. D1, D3: Display directory on CRT.
445B	17499	L3. Update directory with current record as end of file. N1, N3: Select and power up specified drive.
445D	17501	L1. Calculate EOF record number.
445E	17502	L3. Reread current sector. N1, N3: Test drive and disk.
4460	17504	L1. Skip next logical record.
4461	17505	L3. Rewrite current sector. N1, N3: Add user routine to DOS library chain.
4462	17506	D1, D3. Send text to printer.
4463	17507	L1. Read directory to buffer or CRT.
4464	17508	L3. Skip next logical record. N1, N3: Remove user routine from DOS library chain.
4467	17511	L1, L3, D1, D3, N1, N3, M1, M3. Display text on CRT.
446A	17514	L1, L3, N1, N3, M1, M3. Send text to printer.
446D	17517	T1, L1, D1, D3, N1, N3, M1. Get time in ASCII format. L3: Calculate current logical record number.
4470	17520	L3. Calculate end of file record number.
4473	17523	L3. Holds image of interrupt latch. T1, L1, D1, D3, N1, N3, M1, M3: Add default extension to filespec in FCB. (See also 444BH)
4476	17526	L1, D1, M1, M3: Parse parameters in command line.
4478	17528	NewDOS/80 v2.0 for Model 3 Break Vector (195=Off, 201=On).
4779	17529	L1. Send text to file or device. D1, D3: Scan and evaluate command line.
447B	17531	L1. Send text to job log and CRT. N3: Add task interrupt chain.
447C	17532	D1, D3. Compare filespec to wildcard mask.
447E	17534	L1. Send text to joblog.
447F	17535	D1, D3. Get device number for file or I/O device.
4482	17538	D1, D3. Sort block of memory.
4485	17541	D1. 10 disk I/O functions depending on value in A.
4488	17544	D3. 10 disk I/O functions depending on value in A. D1: Locate device control block for any device.
448B	17547	D1. Locate drive control table for any drive.
44A0	17568	D3. Locate device control block for any device.
44A3	17571	D3. Locate drive control table for any drive.
44B8	17592	L1. Check drive and disk.
44BB	17595	L1. Get file name from directory.
44C1	17601	L1. Multiply 16 bit by 8 bit integer.
44C4	17604	L1. Divide 16 bit by 8 bit integer.
44D2	17618	M3. Add task to interrupt chain.
44D5	17621	M3. Remove task from interrupt chain.
44D8	17624	M3. Change execution address of task in interrupt chain.
44DB	17627	M3. Set task pointer to default of RET.
44DE	17630	M1, M3. Verify a sector without reading to RAM.
44E1	17633	M1, M3. Read sector.
44E4	17636	M1, M3. Write sector.
44E8	17640	M1, M3. Read directory sector.
44EB	17643	M1, M3. Write directory sector.
44EE	17646	M1, M3. Read director.
44F1	17649	M1, M3. Write directory.
44F4	17652	M1, M3. User function.
44F7	17655	M1, M3. Get directory track number.
46DD	18141	RDSECT. On Model I, allows you to read a disk sector. Register C contains the drive selcted, D contains the track, E contains the sector number, HL points at data buffer. On return, Z is set if successful; otherwise A contains error code.
46E6	18150	WTSECT. On Model I, allows you to write a disk sector. Same conditions as RDSECT at 46DDH.
4754	18260	L1, L3. Select drive.
4759	18265	L1, L3. Continually reselect drive until it is ready.
475E	18270	L1, L3. Seek specified cylinder (track).
4763	18275	L1, L3. Write sector to disk.
4768	18280	L1, L3. Write system (directory) sector.
476D	18285	L1, L3. Write track to disk (used for formatting).
4772	18290	L1, L3. Verify sector without transfering data to memory.
4777	18295	L1, L3. Read sector to buffer.
478F	18319	L1, L3. Get address of drive code table for specifed drive.
479C	18332	L1, L3. Get byte field from drive code table.
4B10	19216	L1, L3. Read directory sector with specified entry code.
4B1F	19231	L1, L3. Write system buffer to specified directory sector.
4B45	19269	L1, L3. Read directory sector to user buffer.
4B64	19300	L3. Get cylinder (track) number of directory.
4B65	19301	L1. Get cylinder (track) number of directory.
4B6B	19307	L3. Multiply 8 bit by 8 bit integers.
4B6C	19308	L1. Multiply 8 bit by 8 bit integers.
4B7A	19322	L3. Divide 8 bit by 8 bit integers.
4B7B	19323	L1. Divide 8 bit by 8 bit integers.

Model III RS-232 Ports – Luis M. Garcia-Barrio

This section contains a list of Model III RS-232 Ports

PORT E8H (232)

Master Reset/MODEM Status Register
Any output to this port resets the Controller.

On input:

Bit 4 — Ring Indicator
Bit 5 — Carrier Detect
Bit 6 — Data Set Ready
Bit 7 — Clear To Send

PORT E9H (233)

Config. DIP switches/Baud rate select

On input:	Bits 0-2 Baud rate from 50 to 1200 (5=300; 7=1200) Bit 3 — 0=Parity On; 1=Parity Off Bit 4 — 0=1 Stop Bit; 1=2 Stop Bits Bit 5-6 Word length ( 00=5, 01=6, 10=7, 11=8 ) Bit 7 — 0=Parity Odd; 1=Parity Even
On output:	Bits 0-3 Receive Baud Rate (50-19200) Bits 4-7 Transmit Baud Rate (50-19200)

PORT EAH (234)

Status and Control Register

On input:	Bit 3 — 1=Parity Error Bit 4 — 1=Framing Error Bit 5 — 1=Overrun Error Bit 6 — 1=Data Sent Bit 7 — 1=Data Ready
On output:	Bit 0 — Data Terminal Ready Bit 1 — Request To Send Bit 2 — Break Bit 3 — Parity enable Bit 4 — Stop bits Bits 5-6 Word length select Bit 7 — Parity

PORT EBH (235)

Data Register

On input:	Received Data
On output:	Transmit Data

Model III/IV Ports

Port	Description
80H	Input: Reserved. Output: Graphics board register.
81H	Input: Graphics board RAM read. Output: Graphics board RAM write.
82H	Input: Reserved. Output: Graphics board Y register.
83H	Input: Reserved. Output: Graphics board X register.
84H	Mod IV – various controls. 80 micro, March 84, p. 122. Input is reserved. Output: Bit 0: Video memory, keyboard memory, and Model III ROM. (See Table 1) Bit 1: Same as bit 0. (See Table 1) Bit 2: Video display mode. 0 = 64 by 16, 1 = 80 by 24. Bit 3: Reverse Video. Bit 4: Ram bank select. (See Table 2) Bit 5: Ram bank select. (See Table 2) Bit 6: Ram bank select. (See Table 2) Bit 7: Video page select (64 by 16 mode) 0 = page 0, 1 = page 1.
85H – 87H.	Same as 84H.
88H	CRT controller control register.
89H	CRT controller control register.
8AH	CRT controller control register.
8BH	CRT controller data register.
8CH – 8FH.	Graphics board select 2.
90H	Model IV sound port. Any of the sound routines used on the Model I and Model III that uses port FFH can be changed to this and then the Model IV’s built in speaker can be used!
91H – 93H.	Same as 90H.
94H – BFH.	Reserved.
C0H	Input: Hard disk write protect. Output: Reserved.
C1H	Hard disk control register.
C2H – C3H.	Input: Hard disk device ID register. Output: Reserved.
C4H	Hard disk CTC channel 0.
C5H	Hard disk CTC channel 1.
C6H	Hard disk CTC channel 2.
C7H	Hard disk CTC channel 3.
C8H	Hard disk data register.
C9H	Hard disk error register.
E0H	Maskable interupt
E4H	Select NMI options/read NMI status
E8H	–
E9H	—— RS-232
EAH	—— ports
EBH	–
ECH	Write = various controls/ read = reset clock Bit 7 not used Bit 6 CPU clock speed [0 = 2 mhz, 1 = 4 mhz (Mod IV only)] Bit 5 Video waits [0 = disable, 1 = enable] Bit 4 I/O bus [0 = disable, 1 = enable] Bit 3 Alt. char. [0 = disable, 1 = enable] Bit 2 Double width [0 = normal, 1 = double] Bit 1 Cass motor [0 = on, 1 = off] Bit 0 not used
NOTE : Ports F0H through F4H are for Model III/IV disk I/O (not Model I)
F0H	Read FDC status/issue FDC command Read status 80H Not ready 40H Write protect 20H Record type/Write fault/Head loaded 10H Seek error/Record not found 08H CRC error 04H Track 0/lost data 02H Index/DRQ 01H Busy
F1H	FDC track register
F2H	FDC sector register
F3H	FDC data register
F4H	Select drive and options
F8H	Line printer addres port 80H Busy. 40H Out of paper 20H Unit select 10H Fault
FFH	Cassette port

FDC commands via port F0 (Model III only)
00H	restore
80H	read sector
A0H	write normal sector
A1H	write read protect sector
C0H	read address
D0H	reset; puts FDC in mode 1
E0H	read track
F0H	write track

Table 1
	Bits 1 0		Model III ROMs Enabled	Video and Keyboard Status.
	0	0	Yes	Model III.
	0	1	No	Model III.
	1	0	No	Model 4. (In)
	1	1	No	Model 4. (Out)

Table 2
	Bits 6 5 4	Lower 32k RAM	Upper 32K RAM
	0 0 0	Bank 0	Bank 1
	0 1 0	Bank 0	Bank 2
	0 1 1	Bank 0	Bank 3
	1 1 0	Bank 2	Bank 1
	1 1 1	Bank 3	Bank 1

ROM Addresses

The following Z80 registers and register pairs apply: A,F,B,C,D,E,H,L,AF,BC,DE,HL,IX,IY. Any of these proceeded by a “‘” refers to the alternate set.
Miscellaneous: SA – Software accumulator SA1 – Alternate software accumulator RA – Register accumulator (E,D,C,B).

Hex	Dec.	Label	Type	Description
0000	0	DOSCLD	Jp	“In cassette systems, reset computer; in disk systems, cold boot of DOS. Could also be done via RST 00H.”
0008	8	SYNTAX	RST	Checks for syntax. HL points to byte to be checked and proper byte follows RST 08H instruction.
000B	11	WHERE	Call	“Vector used to resolve relocation address of calling routine. On exit, HL points to address following Call instruction.”
0013	19	GET	Call	This routine gets a byte from a logical device or a file that is open. Entry: DE points at FCB. Exit: A = byte.
0018	24	CP16	Rst	Compare DE and HL as 16 bit unsigned intergers.
001B	27	PUT	Call	Outputs a byte to a logical device or FCB. DE = FCB and A = byte. Don’t confuse with CTL at 0023.
0023	35	CTL	Call	Outputs a control byte to a logical device or FCB. DE = FCB and A = control byte.
0028	40		Rst	Pressing Break key RST’s here and then jumps to location 400CH. Also normal DOS function vector.
002B	43	KBDSCN	Call	Scan keyboard and return with accumulator containing result. DE is used.
0033	51	VDCHAR	Call	Displays a character at current cursor location.
003B	59	PRCHAR	Call	“Waits until printer is ready then prints charatcter. A = ASCII character. If BREAK is pressed, a return to caller is made.”
0040	64	KBLINE	Call	Call Input a line from the keyboard. B = max length of line. HL points at buffer. Buffer should be the length of B plus 1. To terminate, hit BREAK or ENTER. On exit, HL points at buffer and B = number of characters entered. Carry will be set if BREAK was pressed.
0049	73	KBWAIT	Call	“Scans the keyboard until a key is pressed. If BREAK is pressed, it is returned like other keys.”
0050	80	RSRCV	Call	“Recieve a character from RS-232. No entry conditions. On exit, memory location 16872 contains character recieved. DE is altered. This routine honors wait status.”
0055	85	RSTX	Call	“Transmit character to RS-232. On entry, Accumulator or memory location 16880 contains character. On exit, 16880 = 0 if no character sent. Wait status honored.”
005A	90	RSINIT	Call	Call Initialize RS-232 interface. On entry, memory location 16888 = send/recieve baud rate code, location 16890 = wait/don’t wait switch, location 16889 = RS-232 characteristics switch. On exit, DE is altered. For more detail, consult Model 3 reference manual.
0060	96	DELAY	Call	“Load BC with how many times to loop, then call.”
0069	105	INITIO	Call	“Initialize all I/O drivers to their ROM routines. No entry conditions. On exit, all registers changed.”
006C	108	ROUTE	Call	“On entry, location 4222H = two byte source device ASCII abbreviation and location 4220H = two byte destination ASCII abbreviation. On exit, DE is altered.”
0072	114			An alternative for entering Basic. See also 1A19H.
00B1	177			Type in SYSTEM (even from DISK BASIC) and reply to the “*?” prompt with /177. The computer will then ask you for memory size. Upon return, you’ll still be in DISK BASIC, but your program will be gone. Also, it doesn’t get along with any high memory routines present.
00FA	250			Call this routine from BASIC and your computer will brag about it having Level II or Model III BASIC.
0132	306	POINT		Basic’s POINT routine.
0135	309	SET		Basic’s SET routine.
0138	312	RESET		Basic’s RESET routine.
0150	336	GRAPH	Jp	This is the routine that is Basic’s SET, RESET, and POINT functions. Here’s how to use it. Load HL with return address and push. Load register A with one of the following: 00H = POINT, 01H = RESET, and 80H = SET. Push AF onto stack. Load A with X coordinate and push onto stack. Load A with Y coordianate and JP GRAPH.
018C	396		Call	“Checks for syntax of “”)”" via RST 08H.”
01C9	457	CLS	Call	Clear screen.
01D3	467	RANDOM	Call	Randomize.
01F8	504	CSOFF	Call	This routine turns off the cassette drive.
0212	530	DEFCAS	Call	A register contains a 0 or 1 which is the cassette number. This routine defines cassette number and turns on cassette. Model I only.
022C	556	???	???	???
0235	565	CSIN	Call	Inputs data one byte at a time from cassette after you use CSHIN. A = the data byte.
0264	612	CSOUT	Call	Outputs data one byte at a time to cassette after you use CSHWR. A = the output byte.
0287	647	CSHWR	Call	Turns on the cassette and writes the header.
0296	662	CSHIN	Call	Finds the cassette header info at the beggining of cassette file.
02B2	690	SYSTEM		Basic’s SYSTEM routine.
0314	788	???	???	???
032A	810	OUTCHR	Call	Ouput character in register A; OUTSEL (409CH) selects device. See OUTSEL for device values.
033A	826	DISPA	Call	Displays character in A on screen at next print position. Uses AF.
0358	856			Calls keyboard scan routine.
035B	859		Call	Same as 002BH.
0361	865	KIBUFF	Call	Reads keyboard into buffer until a carriage return is entered. 40A7H contains the address of the buffer.
03C2	962			Line printer driver for Model I.
03E3	995			Keyboard driver for Model I. Model III = 3024H.
0458	1112			Video driver for Model I.
0473	1139			Video driver for Model III.
0506	1286	CURCON		“Start of cursor control table. Model I. 80 Microcomputing, Sept. 1980, p. 187.”
0540	1344			End of cursor control table.
058D	1421			Line printer driver for Model I.
05D9	1497	KLINE	Call	Same as KBLINE. See 0040.
06CC	1740			An alternative for entering Basic. See also 1A19H.
06D2	1746			Start of Model 1 interrupts relocated to RAM on boot up.
06E6	1766			End of Model 1 interrupts relocated to RAM on boot up.
06E7	1767			Start of Model 1 keyboard DCB.
06EE	1774			End of Model 1 keyboard DCB.
06EF	1775			Start of Model 1 Video DCB.
06F6	1782			End of Model 1 Video DCB.
06F7	1783			Start of Model 1 Printer DCB.
06FE	1790			End of Model 1 Printer DCB.
0713	1811	SUBSP	Call	Subtract SA from RA; result in SA.
0716	1814	ADDSP	Call	Add RA and SA; result in SA.
0778	1912	RSETSA	Call	“If SA contains a 00H, RND generates a number between 0 and 1. Use this call to place a 00H in SA.”
0809	2057	LOG	Call	Basic’s LOG function.
0847	2119	MLTSP	Call	Multiply RA and SA; result in SA.
08A2	2210	DIVSP	Call	Divide RA by SA; result in SA.
0977	2423	ABS	Call	Basic’s ABS function.
0982	2434	MVVAR	Call	Move number of bytes shown by typeflag from area pointed to by DE to area pointed to by HL.
098A	2442	SGN	Call	Basic’s SGN function.
09A4	2468	LDSTSA	Call	Load SA into stack.
09B1	2481	LDSAHL	Call	Load single precision number pointed to by HL into SA.
09B4	2484	LDSARA	Call	Load RA into SA.
09BF	2495	LDRASA	Call	Load SA into RA.
09C2	2498	LDRAHL	Call	Load single precision number pointed to by HL into RA.
09CB	2507	LDHLSA	Call	Load SA into area pointed to by HL.
09D2	2514	LDDEHL	Call	Load single precision number pointed to by HL into area pointed to by DE; needs FLAGSP.
09D3	2515	LDHLDE	Call	Load single precision number pointed to by DE into area pointed to by HL; needs FLAGSP.
09D6	2518	MOVEA	Call	“Move data; DE = source, HL = destination, A = how much to move.”
09D7	2519	MOVEB	Call	“Same as above, except B contains the count.”
09F7	2551	MVSAHL	Call	Move number pointed to by HL into SA; needs FLAGDP.
09FC	2556	MVALT	Call	Move SA into SA1.
0A0C	2572	CPSP	Call	Compare RA and SA1.
0A39	2617	CPINT	Call	Compare DE and HL.
0A78	2680	CPDP	Call	Compare SA and SA1.
0A7F	2687	GETPAR	Call	Load parameter in USR(x) into HL; this must be first instruction of USR call. Also used for CINT function.
0A9A	2714	BSCPAR	Jp	Return to Basic program with parameter.
0A9D	2717	FLAGIN	Call	Set typeflag of SA to interger.
0AB1	2737	CSASP	Call	Convert SA to single precision. Also Basic’s CSNG routine.
0ACC	2764	CHGIS	Call	Value in workspace/accumulator is changed from integer to single precision.
0ADB	2779	CSADP	Call	Convert SA to double precision. Also Basic’s CDBL routine.
0AEC	2796	FLAGDP	Call	Set typeflag for SA to double precision.
0AEF	2799	FLAGSP	Call	Set typeflag for SA to single presision.
0B26	2854	FIX	Call	Basic’s FIX function.
0B37	2871	INT	Call	Basic’s INT function.
0BC7	3015	SUBINT	Call	Subtract HL from DE; result in HL and SA if no overflow (flag = 2); result in SA only if overflow (flag = 4).
0BD2	3026	ADDINT	Call	Add DE and HL; result in HL and in SA if no overflow.
0BF2	3058	MLTINT	Call	“Multiply DE and HL; result in HL and SA if no overflow (flag=2), result in SA only if overflow (flag=4)”
0C70	3184	SUBDP	Call	Subtract SA1 from SA; result in SA.
0C77	3191	ADDDP	Call	Add SA and SA1; result in SA.
0DA1	3489	MLTDP	Call	Multiply SA and SA1; result in SA.
0DE5	3557	DIVDP	Call	Divided SA by SA1; result in SA.
0FAF	4015			Display integer number in HL in ASCII decimal. The ASCII number will also be in memory at 4131H – 4135H.
0FBD	4029	CSAASC	Call	Convert SA (set typeflag) to ASCII. Result (in dec) is placed in buffer starting at 4130H and terminated by a 00H byte and HL = 4130H.
13E7	5095	SQR	Call	Basic’s SQR function.
13F7	5111	POWER	Call	Raise RA to the power SA; result in SA.
1439	5177	EXP	Call	Basic’s EXP function.
14C9	5321	RND	Call	Basic’s RND function.
14CC	5324			???
1541	5441	COS	Call	Basic’s COSine function.
1547	5447	SIN	Call	Basic’s SIN function.
15A8	5544	TAN	Call	Basic’s TAN function.
15BD	5565	ATN	Call	Basic’s ATN function
1608	5640			“Beginning of jump table for Basic’s functions. For Basic’s jump statement table, see 1822H.”
164F	5711			End of jump table for Basic’s functions.
1650	5712			Beginning of table of names of Basic’s reserved words.
181F	6175			End of table of names of Basic’s reserved words.
1822	6178			“Beginning of jump table for Basic’s statements. For Basic’s jump funtion table, see 1608H.”
1899	6297			End of jump table for Basic’s statements.
18C9	6345			“Start of BASIC error messages. Ie: NF, OM, etc.”
18F6	6390			End of BASIC error messages.
196C	6508			Check for enough RAM for stack operation.
1997	6551			SN ERROR routine.
19A2	6562			ERROR routine.
1A19	6681	BASIC	Jp	“Return to Basic and display Basic READY prompt (if you have difficulty with 1A19, try 06CCH or 0072H instead)”
1AF8	6904			Writes line pointers beginning from start of Basic program.
1AFC	6908			Writes line pointers beginning with line pointed to by DE.
1B2C	6956	FNDLIN		“To use: Load DE with line number, call and this location. Upon exit, BC will contain location. 80 Micro, Feb. 1981, p. 148.”
1B49	6985	NEW		Basic’s NEW routine.
1B4D	6989			“Reset Basic pointers? 80 Microcomputing, Nov 81, p. 386.”
1B5D	6705			Basic initialization routines (RUN).
1BC0	7104	TOKEN		Basic’s tokenizing routine. Point register pair HL to the start of the string to be tokenized terminated by a 0 byte and call 1BC0H. Upon exit, HL will point to one byte below the tokenized string which will be terminated by a 0 byte.
1CA1	7329	FOR		Basic’s FOR routine.
1D1E	7454	RUNSTM	Jp	“HL points at “”:”" or 00H terminating a Basic statement or line; execution will proceed from next statement.”
1D91	7569	RESTORE		Basic’s RESTORE routine.
1D9B	7579			Scan for shift @ and BREAK.
1DA9	7593	STOP		Basic’s STOP routine.
1DAE	7598	END		Basic’s END routine.
1DE4	7652	CONT		Basic’s CONT routine.
1DF7	7671	TRON		Basic’s TRON routine.
1DF8	7672	TROFF		Basic’s TROFF routine.
1E00	7680	DEFSTR		Basic’s DEFSTR routine.
1E03	7683	DEFINT		Basic’s DEFINT routine.
1E06	7686	DEFSNG		Basic’s DEFSNG routine.
1E09	7689	DEFDBL		Basic’s DEFDBL routine.
1E4A	7754	FCERR	Call	“Prints “”FC Error”".”
1E5A	7770	VAL	Call	“Convert a string representing a decimal number and terminated by a 00H byte to a binary number. HL points at first character, DE contains result after call.”
1E7A	7802	CLEAR		Basic’s CLEAR routine.
1EA3	7843	RUN		Basic’s RUN routine.
1EB1	7857	GOSUB		Basic’s GOSUB routine.
1EC2	7874	GOTO		Basic’s GOTO routine.
1EDE	7902	RETURN		Basic’s RETURN routine.
1F05	7941	DATA		Basic’s DATA routine.
1F07	7943	REM/ELSE		Basic’s REM and/or ELSE routine.
1F21	7969	EVALU	Call	Call Evaluate expression. Useful for doing complicated math functions in machine language. HL must point to a portion of memory that is in tokenized BASIC and terminated by a 00H byte or a “:” byte. Also known as Basic’s LET routine.
1F6C	8044	ON		Basic’s ON routine.
1FAF	8111	RESUME		Basic’s RESUME routine.
1FF4	8180	ERROR		Basic’s ERROR routine.
2008	8200	AUTO		Basic’s AUTO routine.
2039	8249	IF		Basic’s IF routine.
2067	8295	LPRINT		Basic’s LPRINT routine.
206F	8303	PRINT		Basic’s PRINT routine.
219A	8602	INPUT		Basic’s INPUT routine.
21E3	8675	MVSTR	Call	Move string into space; HL points at first byte of buffer and BC points at variable name.
21EF	8687	READ		Basic’s READ routine.
22B6	8886	NEXT		Basic’s NEXT routine.
2337	9015			“Gets a general (string, integer, single, or double precision) parameter in the accumulator and sets the type flag (40AFH) accordingly.”
2490	9360	DIVINT	Call	Call Divide DE by HL; result in SA in single precision format. 2540 9536 LDVAWS Call Loads value of variable into workspace/ accumulator. On entry, HL points to first character of variable name. On exit, HL points to first character following variable name.
25A1	9633	CPSTR	Call	“Compare two strings. HL and BC point at strings, D and E contain lengths.”
2608	9736	DIM		Basic’s DIM statement.
260D	9741	VARPTR	Call	“Get variable address in DE, HL points at variable name.”
27D4	10196	FRE		Basic’s FRE routine.
27F5	10229	POS		Basic’s POS routine.
2836	10294	STR$		Basic’s STR$ routine.
28A7	10407	OUTSTR	Call	“Output string terminated by a 00H byte or 22H (“”) byte.; HL points at first character, OUTSEL (409CH) selects device. See OUTSEL for device numbers.”
2A03	10755	LEN		Basic’s LEN routine.
2A0F	10767	ASC		Basic’s ASC routine.
2A1F	10783	CHR$		Basic’s CHR$ routine.
2A61	10849	LEFT$		Basic’s LEFT$ routine.
2A91	10897	RIGHT$		Basic’s RIGHT$ routine.
2A9A	10906	MID$		Basic’s MID$ routine.
2AEF	10991	INP		Basic’s INP routine.
2A2F	10799	STRING$		Basic’s STRING$ routine.
2AC5	10949	VAL		Basic’s VAL routine.
2AFB	11003	OUT		Basic’s OUT routine.
2B02	11010			Gets a two byte integer in DE.
2B17	11031			“Evaluate expression? 80 Microcomputing, Nov 81, p. 386″
2B1C	11036			Gets a one byte integer in A.
2B29	11049	LLIST		Basic’s LLIST routine.
2B2E	11054	LIST		Basic’s LIST routine.
2B75	11125	OSTR	Call	“Output string to current device. On entry, HL points to first character in string which ends in a 00 byte.”
2B7E	11134			“Write line of Basic in buffer, change tokens to words.”
2BC6	11206	DELETE		Basic’s DELETE routine.
2BF5	11253	CSAVE		Basic’s CSAVE routine.
2C1F	11295	CLOAD		Basic’s CLOAD routine.
2C77	11383			“Initialize for Basic. 80 Micro, Sep. 1980, p. 72.”
2CAA	11434	PEEK		Basic’s PEEK routine.
2CB1	11441	POKE		Basic’s POKE routine.
2E60	11872	EDIT		Basic’s EDIT routine.
2E66	11878	EDITOR		“Load HL with line number to edit and use this routine. 80 Micro, Feb. 1981, p. 148.”
3024	12324			Video driver for Model III.
3033	12339	GETDAT	Call	“Get date in ASCII format. Mod III TRSDOS, LDOS, & MULTIDOS.”
3036	12342	GETTIM	Call	“Get time in ASCII format. Mod III TRSDOS, LDOS, & MULTIDOS.”
3042	12354	???	???	???
37E0	14304		Port	“Model I interrupt address port. Bit 7 set for clock, bit 6 set for disk.”
37E1	14305		Port	Model I disk drive select.
37E4	14308		Port	Model I cassette 1 or 2 select (0 or 1).
37E8	14312		Port	Lineprinter address port.
37EC	14316		Port	Model I disk command/status.
37ED	14317		Port	Model I disk track select.
37EE	14318		Port	Model I disk sector select.
37EF	14319		Port	Model I disk data.
3800	14336		Ports	Beginning of model I & III keyboard address ports.
3840	1440		Ports	End of model I & III keyboard address ports.

Radio Shack 5/15 Meg HD Port Assignments – Bob Haynes, 10/15/87

This chart provides reference on the Western Digital Hard Disk Controller board WD1000-TB1, based on the WD1010 controller chip and WD1100 support chip. This board is used in later (white) versions of the Radio Shack 15 Meg Hard Disk (26-4155).

Earlier versions of the 15M, the 5M, and 12M hard disk systems all use a larger controller board based on the 8X300 controller chip. I’ve heard the R/S 8M hard disk also uses the 8X300 board, but that’s unconfirmed.

I have little information on the 8X300 board, but since both 15 and 5 Meg systems are known to work with the same driver/format software from at least three sources (Tandy/MISOSYS/PowerSOFT), it is assumed most of this chart also applies to the earlier 8X300 board. (one difference is noted above)

Although Radio Shack has mapped the HD access ports from C0-CFH as a standard configuration, both boards can re-map the ports to 50-5FH, 60-6FH, or 70-7FH simply by changing some jumpers. (If interested, drop a line for details.)

Special thanks to Adam Rubin, who reviewed the information to help confirm its accuracy. Comments, corrections and updates are welcome!

                 Radio Shack 5/15 Meg HD Port Assignments
.--------------------------------------------------------------------------.
|PORT C0H - READ ONLY                |PORT C1H - R/W - HD Control Register |
|Bits 2-3 unused                     |Bits 0-2, 5-7 unused (see note 4)    |
|     0-INTRQ-Interrupt request      |     3    If set, enables controller |
|     1-HWPL-If set, at least one HD |     4    If set, resets controller  |
|            is write protected      |-------------------------------------|
|     4-WPD4-drive 4 write protected |PORT C2-C3H - READ - HD Dev. ID Reg. |
|     5-WPD3-drive 3 write protected |     C4-C7H - HD CTC Channels 0-3    |
|     6-WPD2-drive 2 write protected |     See note 1                      |
|     7-WPD1-drive 1 write protected |-------------------------------------|
|------------------------------------|PORT C8H - R/W - HD Data Register    |
|PORT C9H - READ - Error Register    |-------------------------------------|
|Bits 3,5 all reserved (zero)        |PORT C9H - WRITE - Wrt Pre-Comp Cyl. |
|     0-DAM not found (see note 2)   |The value stored here multiplied x4  |
|     1-Track 0 Error (restore cmnd) |is the RWC start cylinder number.    |
|     2-Aborted Command              |-------------------------------------|
|     4-ID Not Found Error           |PORT CAH - R/W - Sector Count        |
|     6-CRC Data Field Error         |Used only for multiple sector access |
|     7-Bad Block Detected           |don't care w/ single sector commands,|
|------------------------------------|internally decrements when used.     |
|PORT CBH - R/W - Sector number      |-------------------------------------|
|------------------------------------| PORT CDH - R/W - Cylinder MSB       |
|PORT CCH - R/W - Cylinder LSB       |   (bits 0-1 only; max cyls = 1024)  |
|--------------------------------------------------------------------------|
|PORT CEH - R/W - SDH - Sector size/Drive #/Head #                         |
|Bits 0-2  Head number  (0-7)                                              |
|     3-4  Drive number (00-11 reference DSEL1-DSEL4 respectively)         |
|     5-6  Sector size  (00=256, 01=512, 10=1024, 11=128)                  |
|     7    EXTension:   if set, ECC (Error Checking and Correction) codes  |
|                       are in use, R/W data (sector length+7 bytes) do    |
|                       not check/generate CRC.                            |
|--------------------------------------------------------------------------|
|PORT CFH - READ - Error Status Register                                   |
|Bit 0  Error (OR of bits 1-7)       Bit 4  Seek complete                  |
|    1  Command in progress              5  Write fault                    |
|    2  Reserved (0)                     6  Drive ready                    |
|    3  Data request                     7  Busy                           |
|--------------------------------------------------------------------------|
|PORT CFH - WRITE - Command Register Instruction Set - see note 3          |
|          Bits: 7 6 5 4 3 2 1 0    |            Bits: 7 6 5 4 3 2 1 0     |
|  Restore     | 0 0 0 1 d c b a    |  Read Sector   | 0 0 1 0 i m 0 0     |
|  Seek        | 0 1 1 1 d c b a    |  Write Sector  | 0 0 1 1 0 m 0 0     |
|  Scan ID     | 0 1 0 0 0 0 0 0    |  Write Format  | 0 1 0 1 0 0 0 0     |
|                                   |                                      |
| "dcba" defines step rate field:   | "i" defines interrupt enable status: |
|      0000 =  35 us.               |   0 = interrupt when data request    |
| 0001-1111 =  0.5-7.5 ms in        |       line (DRQ*) is enabled         |
|               0.5 ms steps        |   1 = interrupt at end of command    |
|                                                                          |
| "m" defines multiple sector flag: 0 = one sector, 1 = multiple sectors   |
`--------------------------------------------------------------------------'

Notes:
1.  Ports C2-C7 are applicable to the Model II configuration with interface
    board and 8X300 controller board only.  (no further information was
    available, sorry!)

2.  Port C9, bit 0, READ: R/S 15M HD Service Manual indicates this bit is
    reserved (forced zero), but WD1010-00 spec sheet indicates it is used to
    indicate a "DAM not found" error.

3.  Port CF, WRITE: The 4P ROM is known to send three commands to this port:
    16H-restore, 20H-read one sector, 70H-seek. Draw your own conclusions re
    the step rate and interrupt values.

4.  Although there is no formal documentation of this, according to the
    schematics, port C1H bit 2 seems to be used to enable wait state support
    on the 8X300 controller board.  I cannot absolutely confirm this, neither
    can I say whether the later WD-1000-TB1 board implements this function.

Tokenized BASIC – Dick Straw

HOW THE LEVEL II INTERPRETER SEES IT

Dick Straw

Down at the end of appendix C12 in your Level II BASIC Reference Manual you will discover the information that ASCII codes 129 through 191 are graphics codes, and ASCII 192 through 255 are tab codes. And they are. If you run something like

     PRINT CHR$(200); CHR$(140)

You will get a graphic block set spaced appropriately eight spaces from the left margin of your screen. Actually, 128 is a graphics code too — it just doesn’t have any of the six segments of the graphics matrix set, so it comes out blank.

But that only tells part of the story, because those same 128 code values are used by the interpreter as spacesaving symbols equivalent to that list of reserved words on page A115 of the appendix in the manual. Here’s how it works –and how to see it for yourself.

When you start typing a line on your keyboard in the usual fashion, each keystroke is duly recorded in the 110 buffer as its ASCII code equivalent. When you push ENTER at the end of the line, the line you just typed is interpreted right on the spot — in the buffer. Each of the command or instruction words is converted to a single byte equivalent, with values between 128 and 255, inclusive. If there was no number at the beginning of the line, the instructions you just entered will be acted upon at once. If there was a line number, the whole line is transferred to the text memory location and put into its proper place.

Both of those locations can be examined using the PEEK command. The 110 buffer occupies 256 locations beginning at 16870, while the text memory starts at 17129 if you have no disk BASIC entered . I don’t have a printer or a disc, so it takes a lot of staring at the screen, but no big hazards.

Try this: write a short program, say, three lines or so. For example:

     10 DEFINTA,L: DIM A(9)
     20 FOR L = 0 TO 9: A(L) = 5 * L + 2
     30 PRINTA (L);:NEXTL

Then run it. You get the line of ten numbers you expected. Now, in command mode, enter

     FOR Z = 0 TO 200 : ?PEEK(17129 + Z);: NEXTZ

I got a string of numbers like the following you should too, if you used the same spacing I did. I will mark some places as I type this, in order to refer to them later, so remember that the underlining and the letters don’t come with the output.

Most of the numbers here are simply the ASCII codes for the individual letters and numbers used in the program — and the punctuation, too, of course. If you look them up in appendix C, you will find, for example, that 32 is a space and 58 a a colon.

First of all, remember that the program had three lines, numbered 10, 20, and 30. We can see those line numbers in the parts of the text marked B. It is easy to see them if you use line numbers below 256, because the numbers are entered in the usual manner for recording integers, with the least significant byte(LSB) first and the most significant byte (MSB) next, in two bytes. For low numbers, the MSB is zero and the LSB comes out as its real number. For higher numbers, you need to multiply the MSB by 256 and add the LSB to see what you have.

The two numbers ahead of the line numbers are marked B. These, In the same integer format, are the pointers to the next line of the program in the text memory. For example, 252 66 translates to 17148. Since the location of the first number, 252, Is 17129, we count over until we reach 17148 and find a 24, the first byte of the pointer to the third line. The pointer at the beginning of the third line points to a pair of zeroes, marked with an M – this means there is no next line, so the line we were in, in this case line 30, is the last in the program. Since every line of the program ends with a zero (marked E, above) you can locate not only the end of each line but the end of the program as well.

All those other big numbers in the program itself are the function codes I referred to earlier, and you can translate them either by comparison with the program itself or by looking them up in the table of function codes listed there. The first, for example, is 153, the equivalent of DEFINT.

Following the program itself you will find all the variables that were assigned values in the program (that Is why it was worth while to run it .before the PEEK). You need to know that every variable has a three-byte “name” that precedes each value itself. The first byte is a digit that both defines the type of variable and tells how many value-bytes there are. For example, the sequence 2 0 76, marked “L”, is the name of the integer variable L used as an index. The 2 tells you it is stored In two bytes. The next byte is the second symbol In the name, here a zero because we didn’t use a second symbol. It would be 49, the ASCII value of 1 if we had called the variable L1. The MSB of the name is 76, which is ASCII “L”.

The next one is something of a surprise at first. It starts out 4 0 90 — 4 is a single precision variable that needs four bytes for the value, and the name is Z – the variable used in the command line to print out the peek was put in here, shoving the other variables aside. If a double precision variable were used, its indicator would be an 8. After the Z valuer (the value it had when the printing command passed it up), we find the array, A. Its name is that of an integer, but the next values are descriptions of the array – two bytes for the length of the storage string (after the MSB of its value), one byte for the number of dimensions (here 1), and two bytes for the number of locations in each dimension. There is only one dimension here, with ten locations (0 to 9). Then come the ten values, two bytes each.

String arrays have a header beginning with 3, meaning three bytes are in storage. Those three bytes are not its value, obviously, but indicate the length of the string in the first byte (thus a limit of 256 characters), and the integer-format location of the first character in the string. If you assign the string value in the program, as in a print statement, the location pointed to will be in the program text. If it is a string whose value is assigned as a variable, it will be found at the end of the RAM memory.

So there is your whole program, laid out in the memory of your processor for the interpreter to read. And you can read it too. I have included the Hex values for the function codes in the table so that those who get a Hex dump say, from the RSM-1S monitor, can translate it also. Those masochists will also need to translate the ASCII values of letters and numbers from and into Hex, of course!

It is also interesting to look at the I/O buffer. If you type in a long command string, such as the PEEK routine we used to look at the text memory, you will discover that the little program is still there. The first parts of it will be written over as the line is shortened by conversion of the functions to their one-byte codes, and will end with three zeroes, but after that you can find the key-by-key entries you put in when typing.

You can also try this: with your program in residence and after a PEEK, as we did before, en-ter NEW, then run the PEEK on the same area again. You will find that the first two numbers are zeroes — meaning, sorry, no program. You will also find the variable you used to PEEK written in there too. But after that, the rest of the program will be in its original form. You can POKE the original numbers back into locations 17129 and 17130 and list the program again, with only the loss of the first line (if it was long enough not to be overwritten in your playing around).

You can figure out what most of the numbers between 128 and 255 mean by PEEKing at them just as described. But a lot of those numbers don’t mean-anything unless you have disc basic. You can still see what they mean if you try the following:

Entera short program, say, two lines, like this:

     10 A = 10
     20 PRINT A

You know that the text will be located beginning at location 17129, with the first four bytes devoted to the pointer and line number. So POKE into 17133 (the first byte of the program itself) and maybe a couple of others — but be sure not to get past the end of the line, and then LIST the program. Line 10 will be there, and so will the meanings of the numbers you POKEd in. Most of them won’t run, of course, unless you have disc running, but the listing will still do the translating for you.

Tokenized BASIC – Leonard Erickson (a/k/a Shadow)

Each “line” starts with the 2-byte address of the start of the *next* line. Then there’s the line number. Both are binary integers in LSB MSB format. This is followed by the text of the line, with BASIC keywords replaced by one byte tokens. All tokens have bit 8 set.

128     END
129     FOR             170     KILL            211     OR
130     RESET           171     LSET            212     >
131     SET             172     RSET            213     =
132     CLS             173     SAVE            214     <
133     CMD             174     SYSTEM          215     SGN
134     RANDOM          175     LPRINT          216     INT
135     NEXT            176     DEF             217     ABS
136     DATA            177     POKE            218     FRE
137     INPUT           178     PRINT           219     INP
138     DIM             179     CONT            220     POS
139     READ            180     LIST            221     SQR
140     LET             181     LLIST           222     RND
141     GOTO            182     DELETE          223     LOG
142     RUN             183     AUTO            224     EXP
143     IF              184     CLEAR           225     COS
144     RESTORE         185     CLOAD           226     SIN
145     GOSUB           186     CSAVE           227     TAN
146     RETURN          187     NEW             228     ATN
147     REM             188     TAB             229     PEEK
148     STOP            189     TO              230     CVI
149     ELSE            190     FN              231     CVS
150     TRON            191     USING           232     CVD
151     TROFF           192     VARPTR          233     EOF
152     DEFSTR          193     USR             234     LOC
153     DEFINT          194     ERL             235     LOF
154     DEFSNG          195     ERR             236     MKI$
155     DEFDBL          196     STRING$         237     MKS$
156     LINE            197     INSTR           238     MKD$
157     EDIT            198     POINT           239     CINT
158     ERROR           199     TIME$           240     CSNG
159     RESUME          200     MEM             241     CDBL
160     OUT             201     INKEY$          242     FIX
161     ON              202     THEN            243     LEN
162     OPEN            203     NOT             244     STR$
163     FIELD           204     STEP            245     VAL
164     GET             205     +               246     ASC
165     PUT             206     -               247     CHR$
166     CLOSE           207     *               248     LEFT$
167     LOAD            208     /               249     RIGHT$
168     MERGE           209     ^               250     MID$
169     NAME            210     AND             251     (REM QUOTE)

Here are the single byte model 4 codes:

128                     171     AUTO            214     NOT
129     END             172     RENUM           215     ERL
130     FOR             173     DEFSTR          216     ERR
131     NEXT            174     DEFINT          217
132                     175     DEFSNG          218     USING
133     INPUT           176     DEFDBL          219     INSTR
134     DIM             177     LINE            220     '
135     READ            178                     221     VARPTR
136     LET             179                     222
137     GOTO            180     WHILE           223     ERRS$
138     RUN             181     WEND            224     INKEY$
139     IF              182     CALL            225     MEM
140     RESTORE         183     WRITE           226     TIME$
141     GOSUB           184     COMMON          227
142     RETURN          185     CHAIN           228
143     REM             186     OPTION          229
144     STOP            187     RANDOM          230
145     PRINT           188                     231
146     CLEAR           189     SYSTEM          232
147     LIST            190                     233
148     NEW             191     OPEN            234
149     ON              192     FIELD           235
150     WAIT            193     GET             236
151     DEF             194     PUT             237
152     POKE            195     CLOSE           238
153     CONT            196     LOAD            239
154                     197                     240     >
155                     198                     241     =
156     OUT             199     NAME            242     <
157     LPRINT          200     KILL            243     +
158     LLIST           201     LSET            244     -
159     CLS             202     RSET            245     *
160                     203     SAVE            246     /
161                     204                     247     ^
162     ELSE            205     SOUND           248     AND
163     TRON            206                     249     OR
164     TROFF           207     TO              250     XOR
165     SWAP            208     THEN            251     EQV
166     ERASE           209     TAB             252     IMP
167     EDIT            210     STEP            253     MOD
168     ERROR           211     USR             254     \
169     RESUME          212     FN              255
170     DELETE          213     SPC

The 2 byte codes all start with a 255 byte (FFh), the second byte is listed below:

128
129     LEFT$
130     RIGHT$
131     MID$
132     SGN
133     INT
134     ABS
135     SQR
136     RND
137     SIN
138     LOG
139     EXP
140     COS
141     TAN
142     ATN
143     FRE
144     INP
145     POS
146     LEN
147     STR$
148     VAL
149     ASC
150     CHR$
151     PEEK
152     SPACE$
153     OCT$
154     HEX$
155     LPOS
156     CINT
157     CSNG
158     CDBL
159     FIX
160
161
162
163
164
165
166
167
168
169
170     CVI
171     CVS
172     CVD
173     EOF
174     LOC
175     LOF
176     MKI$
177     MKS$
178     MKD$
179     ROW

Tokens - Pete Cervasio

REM is 143. The three byte sequence is :, 143, 251 and in the program below I decode 251 as the single quote.

I've converted this one and my Model 4 converter to Turbo Pascal recently, and they allow things like having the keywords come out in upper/lower/mixed case, and other fun stuff like that. I'll put them up on the web when I get them finished up a little more.

One weird thing: Model 1/3 basic stores literal numbers as the ASCII representation of those numbers. Model 4 basic stores them in the binary representation.

' Model 1/3 compresed BASIC to ASCII format converter thingie
' Copyright (c) 1998, Peter Cervasio (cervasio@airmail.net)
' Permission to distribute freely is granted to all.
DEFINT A-Z

DIM KeyWord$(256)

false = 0
true = NOT false

READ First%, Last%

FOR i = First% TO Last%
        READ KeyWord$(i)
NEXT

PRINT "MOD1BAS - Model 1/3 BASIC to ASCII Conversion Program"
PRINT "Copyright (c) 1997, Pete Cervasio"
PRINT "Distribute freely"
PRINT
PRINT "Model 1/3 BASIC file to convert: ";
LINE INPUT TheFile$
IF TheFile$ = "" THEN END

PRINT "Enter output filename: ";
LINE INPUT OutFile$
IF OutFile$ = "" THEN
  IF INSTR(TheFile$, ".") = 0 THEN
    OutFile$ = TheFile$ + ".qbx"
  ELSE
    OutFile$ = LEFT$(TheFile$, INSTR(TheFile$, ".")) + "qbx"
  END IF
END IF

OPEN TheFile$ FOR BINARY AS 1

A$ = " "
GET 1, , A$

IF A$ = CHR$(255) THEN
  PRINT TheFile$; " -> "; OutFile$
  OPEN OutFile$ FOR OUTPUT AS 2
  WHILE NOT EOF(1)
    GET 1, , i%
    IF i% = 0 THEN END
    GET 1, , i%
    IF i% > 0 THEN
      PRINT #2, LTRIM$(RTRIM$(STR$(i%))); " ";
    ELSE
      PRINT #2, LTRIM$(RTRIM$(STR$(65536! + i%))); " ";
    END IF
    linedone = false
    WHILE NOT linedone
      GET 1, , A$
      IF A$ = CHR$(0) THEN
        linedone = true
      ELSE
        j = ASC(A$)
        IF (j >= First%) AND (j <= Last%) THEN
          PRINT #2, KeyWord$(j);
        ELSE
          PRINT #2, A$;
        END IF
      END IF
    WEND
    PRINT #2, ""
  WEND
ELSE
  PRINT "Could not recognize "; TheFile$; " - 1st byte not 0xFF"
END IF
CLOSE

END

DATA 128, 251
DATA END, FOR, RESET, SET, CLS, CMD, RANDOM, NEXT, DATA, INPUT, DIM
DATA READ, LET, GOTO, RUN, IF, RESTORE, GOSUB, RETURN, REM, STOP
DATA ELSE, TRON, TROFF, DEFSTR, DEFINT, DEFSNG, DEFDBL, LINE, EDIT
DATA ERROR, RESUME, OUT, ON, OPEN, FIELD, GET, PUT, CLOSE, LOAD
DATA MERGE, NAME, KILL, LSET, RSET, SAVE, SYSTEM, LPRINT, DEF, POKE
DATA PRINT, CONT, LIST, LLIST, DELETE, AUTO, CLEAR, CLOAD, CSAVE
DATA NEW, "TAB(", TO, FN, USING, VARPTR, USR, ERL, ERR, STRING$, INSTR
DATA POINT, TIME$, MEM, INKEY$, THEN, NOT, STEP, "+", "-", "*", "/"
DATA "^", AND, OR, ">", "=", "<", SGN, INT, ABS, FRE, INP, POS, SQR
DATA RND, LOG, EXP, COS, SIN, TAN, ATN, PEEK, CVI, CVS, CVD, EOF, LOC
DATA LOF, MKI$, MKS$, MKD$, CINT, CSNG, CDBL, FIX, LEN, STR$, VAL, ASC
DATA CHR$, LEFT$, RIGHT$, MID$, "'"

Pokes and Peeks - Valley TRS-80 Hackers Group (A Levinson and E Bagai)

MODEL	ADDRESSES	FUNCTION

3	0 TO 14335	ROM - LOW MEMORY - BASIC INTERPRETER
3	0 (0000H)	$RESET SOFTWARE SYSTEM RESET
3	43 (002BH)	$KBCHAR SCAN KEYBOARD FOR A CHARACTER
3	51 (0033H)	$VDCHAR DISPLAY A CHARACTER ON THE SCREEN
3	59 (003BH)	$PRCHAR PRINT A CHARACTER ON THE PRINTER
3	64 (0040H)	$KBLINE GET A LINE FROM THE KEYBOARD
3	73 (0049H)	$KBWAIT WAIT FOR A KEYBOARD CHARACTER
3	80 (0050H)	$RSRCV RECEIVE A CHARACTER FROM RS-232-C
1/3	84	UNOFFICIAL PEEK POINT (SEE 293) 1=M1 ELSE=M3
3	85 (0055H)	$RSTX SEND A CHARACTER TO RS-232-C
3	90 (005AH)	$RSINIT INITIALIZE THE RS-232-C
3	96 (0060H)	$DELAY DELAY FOR A SPECIFIED TIME
3	105 (0069H)	$INITIO INITIALIZE I/O DRIVERS
3	108 (006CH)	$ROUTE ROUTE I/O DEVICES
1/3	293	OFFICIAL RADIO SHACK PEEK POINT 73=M3 ELSE=M1
3	457 (01C9H)	$VDCLS CLEAR THE SCREEN
3	473 (01D9H)	$PRSCN PRINT THE SCREEN ON THE PRINTER
3	504 (01F8H)	$CSOFF TURN OFF THE CASSETTE
3	539 (021BH)	$VDLINE DISPLAY A LINE TO THE SCREEN
3	565 (0235H)	$CSIN INPUT A BYTE FROM THE CASSETTE
3	612 (0264H)	$CSOUT OUTPUT A BYTE TO THE CASSETTE
3	647 (0287H)	$CSHWR WRITE THE CASSETTE HEADER
3	653 (028DH)	$KBBRK QUICK SCAN FOR BREAK KEY ONLY
3	662 (0296H)	$CSHIN SEARCH FOR HEADER ON CASSETTE
3	664 (0298H)	$CLKON TURN ON THE CLOCK DISPLAY
3	673 (02A1H)	$CLKOFF TURN OFF THE CLOCK DISPLAY
3	6681 (1A19H)	$READY BASIC READY ENTRY ADDRESS
3	12339 (3033H)	$DATE GET THE SYSTEM DATE
3	12342 (3036H)	$TIME GET THE SYSTEM TIME
3	12354 (3042H)	$SETCAS SELECT CASSETTE BAUD RATE
1	14305	DISK DRIVE SELECT
1	14308	Values: 0-1 SELECT TAPE DRIVE: 0=#1 1=#2
3	14312 (37E8H)	$PRSTAT PRINTER STATUS BYTE
1/3	14312	PRINTER ON=63 OFF=143 (NOT DEPENDABLE)
1	14316	DISK COMMAND/STATUS --
1	14317	DISK TRACK SELECT
1	14318	DISK SECTOR SELECT
1	14319	DISK DATA
1/3	14336 TO 14400	KEYBOARD ADDRESS MATRIX
1/3	14337	SEE 15105
1/3	14338	SEE 15106
1/3	14340	SEE 15108
1/3	14352	SEE 15120
1/3	14368	SEE 15136
1/3	14400	SEE 15168
1/3	14464	SEE 15232
		MEM. 1 2 4 8 16 32 64 128 ...................................... 14337= ` A B C D E F G 14338= H I J K L M N O 14340= P Q R S T U V W 14344= X Y Z 14352= 0 1 2 3 4 5 6 7 14368= 8 9 : ; , - . / 14400=ENT CLR BRK UP DN LT RT SPC 14464=SHF SHF CTL CAP F1 F2 F3 MODEL I IS MAPPED FOR DECIMAL 1 IN THE POSITION 14464 FOR EITHER SHIFT KEY. IN THE MODEL III AND 4, THE LOCATION 14464 WOULD BE DECIMAL 1 FOR THE LEFT SHIFT KEY AND DECIMAL 2 FOR THE RIGHT SHIFT KEY. FOR EXAMPLE, IF PEEK(14340)=16, THEN THE "T" KEY IS BEING PRESSED. OR IF PEEK(14400)=1, THEN THE ENTER KEY IS BEING PRESSED. THIS DOES NOT USE THE INKEY$ ROUTINE, AND THEREFORE YOU CAN HOLD A KEY DOWN INSTEAD OF HITTING IT REPEATINGLY. (USEFUL FOR ACTION GAMES) ALSO, IF TWO KEYS THAT HAVE THE SAME KEYBOARD ADDRESS ARE PRESSED AT THE SAME TIME, THE VALUE WILL BE THE SUM OF THE TWO KEYS. EX: If ENTER and CLEAR are pressed at the same time, location 14400 will equal 3. (UP =Up Arrow DN=Down Arrow, LT=Left Arrow, and RT=Right Arrow)
1/3	15105	Values: 1,2,4,...128 PEEK KEYBOARD RESPECTIVELY: A,B,C,D,E,F,G
1/3	15106	Values: 1,2,4,...128 PEEK KEYBOARD RESPECTIVELY: H,I,J,K,L,M,N,O
1/3	15108	Values: 1,2,4,...128 PEEK KEYBOARD RESPECTIVELY: P,Q,R,S,T,U,V,W
1/3	15112	Values: 1,2,4 PEEK KEYBOARD RESPECTIVELY: X,Y,Z
1/3	15120	Values: 1,2,4,...128 PEEK KEYBOARD RESPECTIVELY: 0,1,2,3,4,5,6,7
1/3	15136	Values: 1,2,4,...128 PEEK KEYBOARD RESPECTIVELY: 8 9 : ; , - . /
1/3	15168	Values: 1,2,4,...128 PEEK: ENTER, CLR,BREAK,UP-ARW,DN-ARW,L-ARW,R-ARW,SPACE
1/3	15232	PEEK KEYBD RT/LT SHIFT
1	15360	Value: 1/65 1:RADIO SHACK LC MOD 65=NOT RS MOD OR L/C DRIVER INSTALLED
1/3	15360 TO 16383	RAM - VIDEO DISPLAY (BEGINS UPPER RIGHT CORNER)
3	16383 (3FFFH)	END OF VIDEO MEMORY
1/3	16387 TO 16389	RST 10H TRANSFER ADDRESS
1/3	16396	Value: 201 RE-ENABLE BREAK KEY
1	16396	Value: 23/221 IN LEVEL II: 23=DISABLES BREAK 221=ENABLES BREAK
3	16396	Value: 175 1ST OF TWO TO DISABLE BREAK (RS RECOMMENDS)
3	16396 (400CH)	BREAK KEY JUMP VECTOR
3	16396	Value: 195 1ST OF 3 COMBINED TO DISABLE BREAK
3	16397	Value: 154 2ND OF 3 COMBINED TO DISABLE BREAK
3	16397	Value: 201 2ND OF TWO TO DISABLE BREAK (RS RECOMMENDS)
3	16398	Value: 10 3RD OF 3 COMBINED TO DISABLE BREAK
1/3	16402 TO 16405	RST 38H TRANSFER ADDRESS
1/3	16405 TO 16412	KEYBOARD CONTROL BLOCK
3	16409	Value: 0/1 0=INPUT LEFT U/L CASE 1=INPUT CONVERTED TO U CASE (UNLESS FOREIGN DRIVER - DOS+)
1/3	16412	Value: 0/1 CURSOR BLINK=0 NO BLINK=1
1/3	16413 TO 16420	VIDEO CONTROL BLOCK
1/3	16414	Value: 141/194 1ST OF 2 TO SEND PRINT TO LPRINT (M1=141 M3=194)
1/3	16415	Value: 5/6 2ND OF 2 TO SEND PRINT TO LPRINT (M1=5 M3=3)
1/3	16414	Value: 88/115 1ST OF 2 TO RESTORE PRINT (VIDEO) (M1=88 M3=115)
1/3	16415	Value: 4 2ND OF 2 TO RESTORE PRINT (VIDEO) (M1 & M3)
1/3	16416 & 16417	CURSOR ADDRESS 2 BYTES LSB/MSB
1/3	16418 or 16419	Value: 32-255 CURSOR CHARACTER IN ASCII (NORMAL CURSOR=171)
3	16420	CHARACTER SET: 1=ALTERNATE 0=REG
1/3	16421 TO 16428	PRINTER CONTROL BLOCK
1/3	16422	Value: 88/15 1ST OF 2 TO SEND LPRINT TO VIDEO (M1=88 M3=115)
1/3	16423	Value: 4 2ND OF 2 TO SEND LPRINT TO VIDEO (M1 & M3)
1/3	16422	Value: 141/194 1ST OF 2 TO RESTORE LPRINT (PRINTER) (M1=141 M3=194)
1/3	16423	Value: 5/3 2ND OF 2 TO RESTORE LPRINT (PRINTER) (M1=5 M3=3)
1/3	16424 (4028H)	MAX PRINTER LINES PER PAGE PLUS 1
1/3	16425	Value: 1 RESETS LINE COUNT
1/3	16425	Value: 1 TO ? PEEKS # LINES PRINTED+1 -- POKE N,1: RESETS LINE COUNT
1/3	16427	MAX CHAR PER LPRINT LINE LESS 2 (255=NO MAX)
1	16445	CASSETTE PORT AND PRINT-SIZE FLAG (BIT 3) COPY
1	16445	Value: 0/8 0=CHR$( 28 ):64 CHAR LINE. 8=CHR$(23):32 CHAR LINE
1	16449 TO 16454	TIME/DATE (SEC,MIN,HRS,YR,DA,MO) (SEE 16919/924)
1	16457 & 16458	DOS MEMORY SIZE
1	16526 & 16527	POINTER TO USR ROUTINE - LEVEL II ONLY
3	16526	NUMBER CHAR PRINTED PER LINE PLUS 1
1/3	16537	INKEY$ STORAGE (IN ASCII)
1/3	16538	ERROR CODE
1/3	16539	e.g.:LPRINT STRING$(N-PEEK(16539),32) . . .
1/3	16539	TO LPRINT TAB(N) WHEN N>63 (SEE NOTE)
1/3	16540	OUTPUT FLAG (-1=KBD 0=VIDEO 1=PRINTER)
1/3	16544 & 16545	STRING SPACE START ADDRESS
1/3	16546 & 16547	CURRENT LINE NUMBER IN BASIC PROGRAM
1/3	16548 & 16549	POINTER TO BEGIN BASIC PROGRAM (SEE NOTE)
1/3	16548	TO APPEND: POKE 16548,PEEK(16633)-2:POKE16549,PEEK(16634)
1/3	16548	TO CLOAD: POKE16548,233:POKE16549,66
1/3	16551 & 16552	WHEN IN BASIC - POINTS TO ADDR OF BASIC KBD BUFFER
1	16553	Value: 255 FOR OLD M1'S -POKE AFTER "INPUT#" FOR A "READ" TO FUNCTION
1/3	16554 TO 16556	SEED FOR RND
1/3	16555	THIS BYTE CHANGED BY 'RANDOM'
1/3	16559	VARIABLE-TYPE FLAG FOR THE SOFTWARE ACCUMULATOR
1/3	16561 & 16562	LAST BYTE OF MEMORY AVAILABLE FOR BASIC
1/3	16598 & 16599	NEXT USABLE BYTE IN STRING SPACE
1/3	16607 & 16608	ENTRY POINT OF SYSTEM TAPE
1/3	16614 & 16615	POINTS AT TERMINATOR OF THE LAST EXECUTED BASIC STATEMENT
1/3	16618 & 16619	LINE # WITH ERROR (IF 65535 : COMMAND MODE)
1	16633 & 16634	POINTER TO END OF BASIC PROG - SEE 16548
1/3	16633 & 16634	STARTING ADDRESS OF SIMPLE VARIABLE TABLE
1/3	16635 & 16636	STARTING ADDRESS OF ARRAY VARIABLE TABLE
1/3	16637 & 16638	1ST BYTE OF FREE MEMORY AFTER ARRAY TABLE
1/3	16639 & 16640	'DATA' POINTER - TELLS YOU WHERE YOU'RE GOING TO RECORD
1/3	16641 TO 16666	VARIABLE-TYPE TABLE
1/3	16669 TO 16676	SOFTWARE ACCUMULATOR (SA)
1/3	16679 TO 16686	ALTERNATE SOFTWARE ACCUMULATOR (SA)
1/3	16722 TO 16815	DISK BASIC INTERFACE
1/3	16806 TO 16868	DOS INTERFACE AREA
1/3	16872 (41E8H)	$RSRCV INPUT BUFFER
4	16875, 16876 & 16883	M4 IN M3 MODE: ASCII VALUES OF F1,2,3 KEYS
1/3	16880 (41F0H)	$RSTX OUTPUT BUFFER
1/3	16884 (41F4H)	Value 103 1st of 2 to Change LINE keyword to act as LPRINT
1/3	16885 (41F5H)	Value 32 2nd of 2 to Change LINE keyword to act as LPRINT
1/3	16888 (41F8H)	$RSINIT BAUD RATE CODE
1/3	16889 (41F9H)	$RSINIT PARITY/WD LEN/STOP CODE
1/3	16890 (41FAH)	$RSINIT WAIT SWITCH (0=DON'T WAIT)
3	16912	Value: 0/8 0=CHR$( 28 ):64 CHAR LINE. 8=CHR$(23):32 CHAR LINE
4/3	16912	Value: 64,0 SPEEDUP IN III MODE, 0=RETURN TO 2MHZ
3	16913	CASSETTE BAUD RATE: 0=500 NON-0=1500
3	16916	Value: 0-7 VIDEO DISPLAY SCROLL PROTECT 1-7 LINES
3	16919	Value: 00-59 SECONDS
3	16920	Value: 00-59 MINUTES
3	16921	Value: 00-23 HOURS
3	16922	Value: 00-99 YEARS
3	16923	Value: 01-31 DAYS
3	16924	Value: 01-12 MONTHS
1/3	16928 (4220H)	$ROUTE DESTINATION (1ST) BYTE
1/3	16929 (4221H)	$ROUTE DESTINATION (2ND) BYTE
1/3	16930 (4222H)	$ROUTE SOURCE (1ST) BYTE
1	17129	BEGINNING OF BASIC PROGRAMS IN LEVEL II BASIC
1	17170	MODEL 1 NEWDOS/80 V2.0 BREAK VECTOR 195=OFF, 201=ON
3	17385 TO --	RAM - BASIC PROGRAM IN A CASSETTE SYSTEM
3	17425 & 17426	MEMORY SIZE M3 DISK BASIC
1	17528	MODEL 3 NEWDOS/80 V2.0 BREAK VECTOR 195=OFF, 201=ON
1/3	19631 (4223H)	$ROUTE SOURCE (2ND) BYTE
3	26841 TO --	RAM - BASIC PROGRAM IN TRS-DOS 1.3
1/3	32767 (7FFFH)	16K SYSTEM TOP OF PHYSICAL MEMORY
3	49151 (BFFFH)	TOP OF MEMORY 32K SYSTEM
3	65535 (FFFFH)	TOP OF MEMORY 48K SYSTEM
... a few more ...
PEEK 14312 If the line printer status port is >63 then the printer is not on or ready to print. Power off =255; print inhibit switch (off line) enabled =233 or 223; print buffer full =191; ready to accept data =63 (normal). PEEK 14316 The disk status register =255 when there is no expansion interface conncected or powered on. POKE 14308,0 Latches cassette #1 14308,1 Latches cassette #2 POKE 16396,23 Disable the BREAK key (Level II) 16396,199 Causes BASIC to reinitialize when the BREAK key is hit (Level II) POKE 16405,0 Locks up the keyboard, but lets your program keep running PEEK 16549 If <66 then this is not Disk BASIC POKE 17170,175 Disable the BREAK key POKE 17171,201 both of these POKEs are necessary POKE 23461,0 Disable the BREAK key (NEWDOS 2.1) POKE 23886,0 Disable the BREAK key (TRSDOS 2.3)

Model III WD1793 Disk Controller Ports

The Model III talks to its WD1793 disk controller through the following ports:

0E4H
Bit 7 6 5	Write 0/1: dis/enable INTRQ intrpt dis/enable DRQ interpt N/A	Read 0/1: INTRQ status: true/false 0/1: DRQ status = true/false 0/1: Reset status = true/false
0F0H
Bit 7 6 5 4 3 2 1 0	Disk Command Register	Disk Status Register Not Ready Write Protect Read: Record Type; Write: Write Fault Record Not Found CRC Error Data Lost DRQ Busy
0F1H (Read/Write) - Disk Track Register
Byte N/A	Write Track Number	Read Track Number
0F2H (Read/Write) - Disk Sector Register
Byte N/A	Write Sector Number	Read Sector Number
0F3H (Read/Write) - Disk Data Register
Byte N/A	Write Data byte to be written to disk	Read Data byte read from disk
0F4H
Bit 7 6 5 4 3 2 1 0	Write Only 0 Selects FM Mode (Single Density) 1 Selects MFM Mode (Double Density) 0 disable wait state generation 1 enable 0 disable write precompensation 1 enables 0 select side 0 1 select side 1 0/1: deselect/select drive 3 0/1: deselect/select drive 2 0/1: deselect/select drive 1 0/1: deselect/select drive 0

UART Bits

One of the minor incompatibilities between the MODEL-I and the MODEL-III lie in the way in which serial (RS-232-C) I/O is handled. they are almost, but not quite the same. This article will discuss the differences, provide patches for SCRIPSIT/LC'S serial printer driver and give some general guidelines for adapting MODEL-I serial I/O code for use on the MODEL-III.

Both the MODEL-I and the MODEL-III use four Z-80 I/O ports for the RS-232-C interface: E8H, E9H, EAH and EBH. The ports are used as follows:

E8H	Outputting any byte to this port resets the uart. This is usually done only when initializing the interface. Inputting a byte from this port places the contents of the modem status register in the a register. see the manual for Radio Shack's RS-232-C Interface (Catalog #26-1145) for details. MODEL-I and MODEL-III use this port in exactly the same way.

E9H	Writing a byte to this port programs the baud rate generator (BRG). The high-order nybble sets the transmit baud rate and the low-order nybble sets the receive baud rate. This is the same for both MODEL-I and MODEL-III. In the MODEL-I, reading this port transfers the settings of the configuration sense switches (the eight dip switches on the RS-232 card) to the a register. these values can then be used for setting the interface to default parameters. the read function for this port is not used in the MODEL-III.

EAH	Writing to this port sets up the UART control parameters and the handshake latch. reading this port transfers the contents of the uart status register to the a register. same for both MODEL-I and MODEL-III.

EBH	Writing to this port loads the transmit data register with the contents of the a register. reading this port transfers the contents of the received data register to the a register. same for both MODEL-I AND MODEL-III.

From this we can see that the only difference between the two machines is that the MODEL-III has no dip switches to read and thus does not have to input from port E9H. A MODEL-III with the RS-232-C interface installed will automatically set up the interface for 300 baud, 8 bit word, 1 stop bit and no parity, when the system boots up. The disk version uses the SETCOM command to change these values as desired. In the MODEL-I, the RS-232-C Interface is not set up by the operating system and must be configured by the user program which will be using the interface. Some simple drivers merely read the dip switches and set the interface accordingly. programs like ST80 can also do this and additionally allow the user to over-ride these default settings with different values. In converting MODEL-I software to run on the MODEL-III, All code relating to the reading of port E9H and setting the interface accordingly must be removed.

Port Add.! D7  ! D6  ! D5  ! D4  ! D3  ! D2  ! D1  ! D0  !
=========!=====!=====!=====!=====!=====!=====!=====!=====!
E8 Write ! <---- UART  RESET & INITIALISATION ONLY ----->!
         !           NO  DATA  BITS  REQUIRED            !  T
---------!-----!-----!-----!-----!-----!-----!-----!-----!
E8 Read  ! cts ! dsr ! cd  ! ri  !  -  !  -  ! rec !  -  !
         !     !     !     !     !     !     ! i/p !     !  R
=========!=====!=====!=====!=====!=====!=====!=====!=====!
E9 Write !   Software Baud rate settings  (see manual)   !
         !     !     !     !     !     !     !     !     !  S
---------!-----!-----!-----!-----!-----!-----!-----!-----!
E9 Read  !Parit! w/l ! w/l ! stop!Parit! Baud! Baud! Baud!
switches !ev/od!slct1!slct2! 1or2!en/di!  1  !  2  !  3  !
=========!=====!=====!=====!=====!=====!=====!=====!=====!  I
EA Write !Parit! w/l ! w/l ! stop!Parit! TX  ! DTR ! RTS !
control  !ev/od!slct1!slct2! 1or2!en/di!en/di!     !     !
---------!-----!-----!-----!-----!-----!-----!-----!-----!
EA Read  ! DAV ! TBMT!o/run!frame!Parit!  -  !  -  !  -  !  8
 Uart    !     !     !error!error!error!     !     !     !
=========!=====!=====!=====!=====!=====!=====!=====!=====!
EB Write ! <---------- 8 BIT DATA  to  UART -----------> !  0
EB Read  ! <---------- 8 BIT DATA from UART -----------> !
========='====='====='====='====='====='====='====='====='---
           D7    D6    D5    D4    D3    D2    D1    D0
=========v=====v=====v=====v=====v=====v=====v=====v=====v---
F8 Write !  -  !  -  !  -  !  -  !  -  !Uart ! DTR ! RTS !  S
         !     !     !     !     !     !Reset!     !     !
---------!-----!-----!-----!-----!-----!-----!-----!-----!  Y
F8 Read  ! <---------- 8 BIT DATA from UART -----------> !
         !     !     !     !     !     !     !     !     !  S
=========!=====!=====!=====!=====!=====!=====!=====!=====!
F9 Write ! <---------- 8 BIT DATA  to  UART -----------> !
         !     !     !     !     !     !     !     !     !  8
---------!-----!-----!-----!-----!-----!-----!-----!-----!
F9 Read  !TMBT ! CTS ! DSR ! CD  ! PE  ! FE  ! OR  ! DAV !  0
         !     !     !     !     !     !     !     !     !
========='====='====='====='====='====='====='====='====='

Z-80 Instruction Set

                             Table I
               Z-80 Instructions from 00 through 3F

           HEX OCT  OP   AD            HEX OCT  OP    AD
            00 000  NOP                 01 001  LD    BC,nn
          * 08 010  EX   AF,AF'         09 011  ADD   HL,BC
          * 10 020  DJNZ n              11 021  LD    DE,nn
          * 18 030  JR   n              19 031  ADD   HL,DE
            20 040  JR   NZ,n           21 041  LD    HL,nn
          * 28 050  JR   Z,n            29 051  ADD   HL,HL
            30 060  JR   NC,n           31 061  LD    SP,nn
          * 38 070  JR   C,n            39 071  ADD   HL,SP

            02 002  LD   (BC),A         03 003  INC   BC
            0A 012  LD   A,(BC)         0B 013  DEC   BC
            12 022  LD   (DE),A         13 023  INC   DE
            1A 032  LD   A,(DE)         1B 033  DEC   DE
            22 042  LD   (nn),HL        23 043  INC   HL
            2A 052  LD   HL,(nn)        2B 053  DEC   HL
            32 062  LD   (nn),A         33 063  INC   SP
            3A 072  LD   A,(nn)         3B 073  DEC   SP

            04 004  INC  B              05 005  DEC   B
            0C 014  INC  C              0D 015  DEC   C
            14 024  INC  D              15 025  DEC   D
            1C 034  INC  E              1D 035  DEC   E
            24 0D4  INC  H              25 045  DEC   H
            2C 054  INC  L              2D 055  DEC   L
            34 064  INC  (HL)           35 065  DEC   (HL)
            3C 074  INC  A              3D 075  DEC   A

            06 006  LD   B,n            07 007  RLCA
            0E 016  LD   C,n            0F 017  RRCA
            16 026  LD   D,n            17 027  RLA
            1E 036  LD   E,n            1F 037  RRA
            26 046  LD   H,n            27 047  DAA
            2E 056  LD   L,n            2F 057  CPL
            36 066  LD   (HL),n         37 067  SCF
            3E 076  LD   A,n            3F 077  CCF

                            Table II
                Z-80 Instructions from 40 through 7F
                    8-Bit Interregister Transfers

General form:
       OCT          OP    AD
       1(r1)(r2)    LD    REG(r1),REG(r2)
Source is REG(r2), destination is REG(r1), where r1 and r2 are 8-bit registers
(see Table VI).

           HEX OCT  OP   AD            HEX OCT  OP    AD
            40 100  LD   B,B            41 101  LD    B,C
            48 110  LD   C,B            49 111  LD    C,C
            50 120  LD   D,B            51 121  LD    D,C
            58 130  LD   E,B            59 131  LD    E,C
            60 140  LD   H,B            61 141  LD    H,C
            68 150  LD   L,B            69 151  LD    L,C
            70 160  LD   (HL),B         71 161  LD    (HL),C
            78 170  LD   A,B            79 171  ADD   A,C

            42 102  LD   B,D            43 103  LD    B,E
            4A 112  LD   C,D            4B 113  LD    C,E
            52 122  LD   D,D            53 123  LD    D,E
            5A 132  LD   E,D            5B 133  LD    E,E
            62 142  LD   H,D            63 143  LD    H,E
            6A 152  LD   L,D            6B 153  LD    L,E
            72 162  LD   (HL),D         73 163  LD    (HL),E
            7A 172  LD   A,D            7B 173  LD    A,E

            44 104  LD   B,H            45 105  LD    B,L
            4C 114  LD   C,H            4D 115  LD    C,L
            54 124  LD   D,H            55 125  LD    D,L
            5C 134  LD   E,H            5D 135  LD    E,L
            64 144  LD   H,H            65 145  LD    H,L
            6C 154  LD   L,H            6D 155  LD    L,L
            74 164  LD   (HL),H         75 165  LD    (HL),L
            7C 174  LD   A,H            7D 175  LD    A,L

            46 106  LD   B,(HL)         47 107  LD    B,A
            4E 116  LD   C,(HL)         4F 117  LD    C,A
            56 126  LD   D,(HL)         57 127  LD    D,A
            5E 136  LD   E,(HL)         5F 137  LD    E,A
            66 146  LD   H,(HL)         67 147  LD    H,A
            6E 156  LD   L,(HL)         6F 157  LD    L,A
            76 166  HALT                77 167  LD    (HL),A
            7E 176  LD   A,(HL)         7F 177  LD    A,A

                            Table III
               Z-80 Instructions from 80 through BF
                   8-Bit Arithmetic and Logic

General form:
       OCT        OP       AD
       2(op3)(r)  OP(op3) [A,]REG(r)
The [A,] field is used with ADD, ADC and SBC to avoid ambiguity with other
instructions.  For the operation codes OP(op3) and the 8-bit register codes
see Table VI.

           HEX OCT  OP   AD            HEX OCT  OP    AD
            80 200  ADD  A,B            81 201  ADD   A,C
            88 210  ADC  A,B            89 211  ADC   A,C
            90 220  SUB  B              91 221  SUB   C
            98 230  SBC  A,B            99 231  SBC   A,C
            A0 240  AND  B              A1 241  AND   C
            A8 250  XOR  B              A9 251  XOR   C
            B0 260  OR   B              B1 261  OR    C
            B8 270  CP   B              B9 271  CP    C

            82 202  ADD  A,D            83 203  ADD   A,E
            8A 212  ADC  A,D            8B 213  ADC   A,E
            92 222  SUB  D              93 223  SUB   E
            9A 232  SBC  A,D            9B 233  SBC   A,E
            A2 242  AND  D              A3 243  AND   E
            AA 252  XOR  D              AB 253  XOR   E
            B2 262  OR   D              B3 263  OR    E
            BA 272  CP   D              BB 273  CP    E

            84 204  ADD  A,H            85 205  ADD   A,L
            8C 214  ADC  A,H            8D 215  ADC   A,L
            94 224  SUB  H              95 225  SUB   L
            9C 234  SBC  A,H            9D 235  SBC   A,L
            A4 244  AND  H              A5 245  AND   L
            AC 254  XOR  H              AD 255  XOR   L
            B4 264  OR   H              B5 265  OR    L
            BC 274  CP   H              BD 275  CP    L

            86 206  ADD  A,(HL)         87 207  ADD   A,A
            8E 216  ADC  A,(HL)         8F 217  ADC   A,A
            96 226  SUB  (HL)           97 227  SUB   A
            9E 236  SBC  A,(HL)         9F 237  SBC   A,A
            A6 246  AND  (HL)           A7 247  AND   A
            AE 256  XOR  (HL)           AF 257  XOR   A
            B6 266  OR   (HL)           B7 267  OR    A
            BE 276  CP   (HL)           BF 277  CP    A

                            Table IV
                Z-80 Instructions from C0 through FF

           HEX OCT  OP   AD            HEX OCT  OP    AD
            C0 300  RET  NZ             C1 301  POP   BC
            C8 310  RET  Z              C9 311  RET
            D0 320  RET  NC             D1 321  POP   DE
            D8 330  RET  C            * D9 331  EXX
            E0 340  RET  PO             E1 341  POP   HL
            E8 350  RET  PE             E9 351  JP    (HL)
            F0 360  RET  P              F1 361  POP   AF
            F8 370  RET  M              F9 371  LD    SP,HL

            C2 302  JP   NZ,nn          C3 303  JP    nn
            CA 312  JP   Z,nn         * CB 313  (See notes)
            D2 322  JP   NC,nn          D3 323  OUT   n,A
            DA 332  JP   C,nn           DB 333  IN    A,n
            E2 342  JP   PO,nn          E3 343  EX    (SP),HL
            EA 352  JP   PE,nn          EB 353  EX    DE,HL
            F2 362  JP   P,nn           F3 363  DI
            FA 372  JP   M,nn           FB 373  EI

            C4 304  CALL NZ,nn          C5 305  PUSH  BC
            CC 314  CALL Z,nn           CD 315  CALL  nn
            D4 324  CALL NC,nn          D5 325  PUSH  DE
            DC 334  CALL C,nn         * DD 335  (See notes)
            E4 344  CALL PO,nn          E5 345  PUSH  HL
            EC 354  CALL PE,nn        * ED 355  (See notes)
            F4 364  CALL P,nn           F5 365  PUSH  AF
            FC 374  CALL M,nn         * FD 375  (See notes)

            C6 306  ADD  A,n            C7 307  RST   00H
            CE 316  ADC  A,n            CF 317  RST   08H
            D6 326  SUB  n              D7 327  RST   10H
            DE 336  SBC  A,n            DF 337  RST   18H
            E6 346  AND  n              E7 347  RST   20H
            EE 356  XOR  n              EF 357  RST   28H
            F6 366  OR   n              F7 367  RST   30H
            FE 376  CP   n              FF 377  RST   38H

                            Table V
           Extended Z-80 Instructions Prefixed by ED
                    Listed by Second Byte

           HEX OCT  OP   AD            HEX OCT  OP    AD

            40 100  IN   B,(C)          41 101  OUT   (C),B
            48 110  IN   C,(C)          49 111  OUT   (C),C
            50 120  IN   D,(C)          51 121  OUT   (C),D
            58 130  IN   E,(C)          59 131  OUT   (C),E
            60 140  IN   H,(C)          61 141  OUT   (C),H
            68 150  IN   L,(C)          69 151  OUT   (C),L
            70 160  (NONE)              71 161  (NONE)
            78 170  IN   A,(C)          79 171  OUT   (C),A

            42 102  SBC  HL,BC          43 103  LD    (nn),BC
            4A 112  ADC  HL,BC          4B 113  LD    BC,(nn)
            52 122  SBC  HL,DE          53 123  LD    (nn),DE
            5A 132  ADC  HL,DE          5B 133  LD    DE,(nn)
            62 142  SBC  HL,HL          63 143  (NONE, see 22H)
            6A 152  ADC  HL,HL          6B 153  (NONE, see 2AH)
            72 162  SBC  HL,SP          73 163  LD    (nn),SP
            7A 172  ADC  HL,SP          7B 173  LD    SP,(nn)

            44 104  NEG                 45 105  RETN
            4C 114  (NONE)              4D 115  RETI

            46 106  IM   0              47 107  LD    I,A
            4E 116  (NONE)              4F 117  LD    R,A
            56 126  IM   1              57 127  LD    A,I
            5E 136  IM   2              5F 137  LD    A,R
            66 146  (NONE)              67 147  RRD
            6E 156  (NONE)              6F 157  RLD

            A0 240  LDI                 A1 241  CPI
            A8 250  LDD                 A9 251  CPD
            B0 260  LDIR                B1 261  CPIR
            B8 270  LDDR                B9 271  CPDR

            A2 242  INI                 A3 243  OUTI
            AA 252  IND                 AB 253  OUTD
            B2 262  INIR                B3 263  OTIR
            BA 272  INDR                BB 273  OTDR

                             Table VI
              Extended Z-80 Instructions Prefixed by CB
                       Listed by Second Byte

       OCT          OP    AD            p  OP(p)
       0(p)(r)      OP(p) REG(r)        0  RLC
       1(n)(r)      BIT   n,REG(r)      1  RRC
       2(n)(r)      RES   n,REG(r)      2  RL
       3(n)(r)      SET   n,REG(r)      3  RR
                                        4  SLA
                                        5  SRA
                                        6  SLO (See notes)
                                        7  SRL

Other octal fields common in Z80 instructions

8-Bit Registers:
  r      0   1   2   3   4   5   6    7
REG(r)   B   C   D   E   H   L  (HL)  A

16 Bit Registers:
  R     0   1   2   3
REG(R) BC  DE  HL  SP

Operations (see Table I):
 op1     0    1      2     3      4    5    6    7
OP(op1) JR  LD/ADD  LD  INC/DEC  INC  DEC  LD   rotate
OP(1) and OP(3) are 16-bit instructions, OP(6) are the immediate loads.
OP(2) is 4 8-bit indexed memory, 2 16-bit and 2 8-bit memeory loads.
OP(7) includes 4 rotates of A, DAA, CPL, SCF and CCF.

Operations (see Table III):
 op3     0    1    2    3    4    5    6    7
OP(op3) ADD  ADC  SUB  SBC  AND  XOR   OR   CP

Operations (see Table IV):
 op4     0         1        2         3        4          5     6    7
OP(op4) RET CN(c) ---  JP CN(c),nn   ---  CALL CN(c),nn  PUSH  op3  RST
OP(5) includes the unconditional CALL plus the prefixes DD, FD, and ED
OP(6) is the immediate 8-bit arithmetic and logical operations ADD A,n etc.

Conditions for JR, JP, CALL, RET
 c     0   1   2   3   4   5   6   7
CN(c) NZ   Z  NC   C  PO  PE   P   M
JR implements only the first four

Notes:

(1)  Instructions in the Z80 but not in the 8080 instruction set are marked
     with an asterisk preceeding the hex instruction in Tables I through IV.
     None of the instructions in Tables V and VI are in the 8080 instruction
     set.  None of the instructions involving the auxiliary index registers
     IX and IY are in the 8080 instruction set.

(2)  The byte CB indicates the first byte of the extended Z80 instructions
     given in Table V.

(3)  The bytes DD and FD are used to prefix instructions using the
     auxiliary index registers IX and IY.  In single-byte instructions,
     using memory location (HL), the memory location pointed to m, where
     m is (IX+d) or (IY+d), may be substituted for (HL) by prefixing the
     instruction by DD or FD, respectively, and spcifying (HL) as the
     source or destination in the instruction format.  The instruction is
     followed by d when this is done and the resulting instruction is
     3 bytes long.

(4)  The byte ED indicates the first byte of the extended Z80 instructions
     given in Table VI.

(5)  Prefixing single-byte 8-bit instructions involving registers H and L
     by DD (for IX) or FD (for IY) results in use of XH, XL, YH or YL
     instead.  This usage is undocumented and works only on Zilog Z80's
     and second-sources which use Zilog masks.  XH, XL, YH and YL refer to
     the high-order bytes of IX and IY, respectively.  ALDS supports these
     instructions.

(6)  The SLO operation in Table V is undocumented and is not well defined.

(7)  All the instructions in Table V can be extended to undocumented Zilog
     Z80 instructions:  These instructions, which use (IX+d) and (IY+d) as
     the source and destination as well as load the result in r, result
     when the (IX+d) or (IY+d) format is used and registers other than
     (HL) are specified.  The resulting instrucions are 4 bytes long.  ALDS
     supports these instructions using the format [OP]LD r,m where m is
     (IX+d) or (IY+d).  The timing is the same as [OP] m.

ROM Calls - Bob Alger (10/27/83)

ROMCALLS is a quick reference to the more common ROM & DOS subroutines, excluding cassette I/O and floating point math. These routines have been assembled from many other publications. Also note that all addresses are in hex except the PEEK/POKE section which is in decimal.

ROM RST VECTORS:

RST     Jump    Contents Purpose
0       none    Re-boot- power on or RESET
8       4000    JP 1C96  If (HL) = ((SP))- do RST10H logic, else print SN error
10      4003    JP 1D78  Find next non-blank character in a string
18      4006    JP 1C90  DE compared to HL.  Z set if DE = HL, C set if DE > HL
20      4009    JP 25D9  Test NTF flag at 40AF.  Z flag set if string, M if
                integer, P&C if single, P&NC if double, A=NTF - 3.
28      400C    RET      BREAK key vector.  you can put your own 3 byte
                instruction here to jump to your own routine.
                NOP
                NOP
30      400F    RET      Used by DOS
                NOP
                NOP
38      4012    EI       Used by DOS
                RET
                NOP

MEMORY MAPPED I/O DEVICES

Address
3000-37DD
37E0
27E4
37E8
37E8
37EC
37EC
37ED
37EE
37EF
3801-3880
3C00-3FFF

Use
NO MEMORY here at all
Disk drive select latch
Cassette drive latch
Line printer data port when storing
Line printer status port when loading
Disk command register when storing
Disk status register when loading
Disk track register
Disk sector register
Disk data register
Keyboard memory
Video display memory

ROM ROUTINES (I/O & MISC.)

Address         Use
0013            Inputs a byte from an input device.
                call:   LD      DE,nnnn ;address of DCB
                        CALL    0013H   ;get byte
                        JP      NZ,NRDY ;input dev not ready

001B            Outputs a byte to an output device.
                call:   LD      DE,nnnn ;address of DCB
                        CALL    001BH   ;put byte
                        JP      NZ,NRDY ;output dev not ready

002B            INKEY subroutine- scans keyboard.  The data is not echoed on
                your screen.  Note that calling 0358H instead will eliminate
                need to save DE.

                call:   PUSH    DE      ;save
                        CALL    002BH   ;scan keyboard
                        POP     DE      ;restore
                        JP      Z,NOKEY ;no key pressed
                        ;key is now in A

0033            DISPLAY subroutine- prints character in A at current cursor
               position on video display.  Cursor position is stored at
               4020-4021.  Note that calling 033AH instead will eliminate
               need to save DE.

               call:    PUSH    DE        ;save
                        LD      HL,nnnn   ;* optionally position cursor
                        LD      (4020H),HL;*   before displaying byte
                        CALL    0033H     ;dislay character
                        POP     DE        ;restore

003B           LPRINT subroutine- prints character in A on line printer.
               Note that calling 039CH instead will eliminate need to save DE.
               call:   PUSH    DE      ;save
                       CALL    003BH   ;print character
                       PNP     DE      ;restore
                       JP      NZ,NRDY ;printer not ready

0049           INPUT subroutine- scans keyboard and waits for key to be
               pressed.  Note that calling 0384H instead will eliminate need
               to save DE.

               call:   PUSH    DE      ;save
                       CALL    0049H   ;wait for key
                       POP     DE      ;restore
                       ;key is now in A

0060           Delay loop in 14.66 microsecond increments.  A value of 0 will
               be equal to .96 seconds.

               call:   PUSH    AF      ;save
                       LD      BC,nnnn ;number of delays
                       CALL    0060H   ;delay a little
                       POP     AF      ;restore

0066           NMI vector.  Jumps here on non-maskable interrupt (ie.
               HALT or press of RESET button). Note- see 41BE.

0150           SET, RESET, POINT graphics functions.  You must make sure
               that the coordinates are within legal range.
               call:   LD      B,nn    ;x coordinate (0-127)
                       LD      A,nn    ;y coordinate (0-47)
                       LD      H,nn    ;POINT=00, RET=80H, RESET=01
                       CALL    GRAPH   ;B, A, & HL will be destroyed
                       LD     A,(4121H);*if POINT was done
                       NR      A       ;*
                       JP      Z,OFF   ;* the point was off
                       JP      ON      ;* the point was on
                       .
                       .
                       .
               GRAPH   PUSH    HL      ;push indicator
                       PUSH    BC      ;push x coordinate
                       LD      HL,DUMMY;fake out BASIC's RST8
                       JP      0150H   ;go do the selected function
               DUMMY   DEFM    ');'    ;make believe this is a BASIC program

01C9           CLS subroutine- homes cursor and clears screen.
               call:   PUSH    AF      ;save
                       CALL    01C9H   ;cls
                       POP     AF      ;restore

02B2           SYSTEM command- prints "*?" and waits for entry.  When
               using the SYSTEM command, if your program machine language
               program has an ORG for 41BEH with a 3 byte instruction
               following, then that 3 byte instruction will be automaticly
               executed after your tape is finished loading.  For example-

                       ORG     41BEH
                       JP      7000H
                       ORG     7000H
               START   .               ;first instruction of your program
                       .
                       .
                       END     START

05D9           LINE INPUT subroutine- accepts a line of keyboard input
               terminated by ENTER or BREAK.  Echoes characters typed
               and recognizes control functions (backspace, shift-backspace,
               etc.).  None of these special characters ever get put into
               your buffer.

               call:   PUSH    DE      ;save
                       LD      B,nn    ;maximum characters allowed to input
                       LD      HL,nnnn ;address of buffer to store characters
               in
                       CALL    05D9H   ;get a line of input
                       POP     DE      ;restore
                       JP      C,BRK   ;BREAK was hit
                       ;B= number of characters typed including
               terminator
                       ;C= original contents of B

06CC           Ref 1A19.

0A7F           Used to pass a 06-bit value to a machine language
               program.
               call:   CALL    0A7FH   ;get value from BASIC
                       ;value now in HL

0A9A           Used to pass a 16-bit value back to BASIC.
               call:   LD      HL,nnnn ;get value to give BASIC
                       JP      0A9AH
                       ;at this point you are back in BASIC with the value.

1A19           Normal entry point for a READY in Level II or Disk BASIC.
               Note that it is better to jump to 06CCH because it does
               not cause an OM error on the first command that follows.

1BB2           Prints "?", inputs up to 241 characters from the keyboard
               and echoes characters typed.  Data goes into BASIC's input
               buffer.  0361H is the same as 1BB3H, less the prompt.
               call:   PUSH    AF      ;save
                       PUSH    DE
                       CALL    1BB3H   ;get input
                       POP     DE      ;restore
                       POP     AF
                       ;HL= points to 1st character minus 1

1D78           (RST10H) Finds next non-blank character in a sting.  It
               increments through string, ignoring spaces and control
               characters 9 & 10 (enters) and returns when the next
               non-blank character is encountered.

               call:    LD      HL,nnnn ;starting address of string minus 1
                        CALL    1D78H   ;search string
                        ;A= non-blank character found
                        JP      Z,END   ;encountered a 00 byte (end of line)
               or ":" (end of statement)
                        JP      C,NBR   ;got an ASCII numeric digit
                        JP      ALPHA   ;not a numeric digit

1E5A           ASCII integer decimal to HEX converter.
               call:    LD      HL,nnnn ;address of ASCII decimal number
                        CALL    1E5AH   ;translate to HEX
                        ;DE= HEX result
                        ;HL= points to first non-decimal character

260D           Point to the VARPTR of a variable.  If the variable
               doesn't exist then create it first.
               call:    LD      HL,nnnn ;point to ASCII variable name
                        CALL    260DH   ;look for/create it
                        ;DE= points to VARPTR of the variable

28A7           PRINT subroutine- prints a string of text on the video
               display, terminated by ENTER (13) or NULL (00), at current
               cursor position.

               call:    PUSH    DE      ;save
                        PUSH    IY
                        LD      HL,nnnn ;address of text
                        CALL    28A7H   ;display text
                        POP     IY      ;restore
                        POP     DE

ROM ROUTINES (INTEGER MATH)

               The following integer math routines make use ACC to contain
               the result of the operation.  ACC is 2 locations in
               memory at 4121 & 4122 (LSB,MSB).  The number type flag (NTF)
               at 40AF must also be set to 02 to indicate integer.

Address        Use
0BD2           Add     - ACC < DE + HL
0BC7           Subtract- ACC = DE - HL
0BF2           Multiply- ACC = DE * HL
2490           Divide  - @BC = DE / HL

               Note that on integer overflow +, -, & * return a single
               precision floating point number in ACC at 4121-4124
               (LSB,LSB,MSB,EXPonent).  Also, / always returns a single
               precision floating point number.  In all cases you should
               check NTF for the type of the result (single= 4).

               Integers are stored in twos compliment form.  Single
               precision floating point numbers are stored as a normalized
               binary fraction, with an assumed decimal point before the most
               significant bit.  Since the msb is always a 1, the most
               significant bit also doubles as the sign bit by making it a 0
               for positive and 1 for negative.  The binary exponent is
               stored in excess 128 form; that is, 128 is added to the
               actual binary exponent needed.  The number 0 is stored as a
               zero mantissa and exponent.  A couple of examples are
               shown below:

Decimal         4121    4122    4123    4124
-------         ----    ----    ----    ----
   0.5          00      00      00      80
   1.0          00      00      00      81
  -1.0          00      00      80      81
 129.0          00      00      01      88
-129.0          00      00      81      88
 257.0          00      80      00      89

----- Arithmetic Accumulator (411D-4124) -----
        Integer         Single          Double
411D                                    LSB
411E                                    LSB
411F                                    LSB
4120                                    LSB
4121    LSB             LSB             LSB
4122    MSB             LSB             LSB
4123                    MSB             MSB
4124                    EXP             EXP

--- Hex Arithmetic Accululator (4127-412E) ---
        Integer         Single          Double
4127    LSB             LSB             LSB
4128    MSB             LSB             LSB
4129                    MSB             LSB
412A                    EXP             LSB
412B                                    LSB
412C                                    LSB
412D                                    MSB
412E                                    EXP

DOS ROUTINES

Address        Use
402D           EXIT is the normal program exit back to DOS.
               call:    JP      402DH

4030           ABORT is the exit back to DOS after an unsuccessful
               program exit.
               call:    JP      4030H

4400           CMD is a routine that accepts a new command to be evaluated.
               call:    CALL    4400H

4405           CMNDI is the entry into the command interpreter.
               call:    ;the following 3 lines are necessary only if this is
               called at the  end  of ` BASIC program
                        LD      HL,402D   ;DOS return address
                        LD      (41FAH),HL
                        LD      SP,41FAH  ;reset stack pointer for DOS use

                        ;your ASCII DOS command should be in the command buffer
                        terminated by a carriage return
                        LD      HL,4318H  ;DOS command buffer
                        JP      4405H     ;if from BASIC
                        CALL    4405H     ;else this way

440D           DEBUG is the entry into the debugging package
               call:    JP      440DH

441C           FSPEC fetches a file specification in TRSDOS standard format.
               call:    CALL    441CH

4420           INIT creates a new file in the directory and opens the DCB
               for this file.  If the filespec name is found then the file
               is simply opened for use, else a new file is created first.
               call:    LD      HL,BUFFER
                        LD      DE,DCB
                        LD      B,LRL
                        CALL    4420H
                        JP      Z,OK      ;no error
                        JP      C,NEWFIL  ;no error, but new file was created
                        ;A= TRSDOS error code

4424           OPEN opens the DCB of an existing file.
               call:    LD      HL,BUFFER
                        LD      DE,DCB
                        LD      B,LRL
                        CALL    4424H
                        JP      Z,OK      ;no error
                        JP      NZ,NOFILE ;file does not exist
                        ;A= TRSDOS error code

4428           CLOSE updates the directory and then closes the file from any
               more processing.
               call:    LD      DE,DCB
                        CALL    4428H
                        JP      Z,OK     ;no error
                        ;A= TRSDOS error code

442C           KILL deletes the directory for an open file and then closes the
               DCB.
               call:    LD      DE,DCB
                        CALL    442CH
                        JP      Z,OK     ;no error
                        ;A= TRSDOS error code

4430           LOAD loads a program file.
               call:    CALL    4430H

4433           RUN loads and executes a program file.
               call:    JP      4433H

4436           READ transfers one logical or physical disk record to
               memory.  See TRSDOS Technical Infromation for complete
               definition.
               call:    LD      HL,UREC
                        LD      DE,DCB
                        CALL    4436H
                        JP      Z,OK      ;no error
                        A= TRSDOS error code (EOF=1CH or 1DH)

4439           WRITE transfers one logical or physical disk record from
               memory.  See TRSDOS Technical Information for complete
               definition.
               call:    LD      HL,UREC
                        LD      DE,DCB
                        CALL    4439H
                        JP      Z,OK      ;no error
                        A= TRSDOS error code

443C           VERF is the same as WRITE except that it vdrifies what
               was written to disk.
               call:    LD      HL,UREC
                        LD      DE,DCB
                        CALL    443C
                        BP      Z,OK      ;no error
                        A= TRSDOS error code

4442           POSN positions a file to READ or WRITE a randomly
               selected logical record.
               call:    LD      DE,DCB
                        LD      BC,nnnn   ;logical record # to position for
                        CALL    4442H
                        JP      Z,OK      ;no error
                        ;A= TRSDOS errnr code

446D           TIME will return the current time in ASCII.
               call:    LD      HL,nnnn   ;address of 8 byte buffer
                        CALL    446DH     ;put time in buffer

4470           DATE will return the current date in ASCII.
               call:    LD      HL,nnnn   ;address of 8 byte buffer
                        CALL    4470H     ;put date in buffer

4AC1           This routine will read sectors 2 - 9 of the disk directory
               track (11H) into your designated buffer.  It is just like the
               DOS routine at 5CC8 which is overlayed by BASIC/CMD.
               ( not for Newdos 80)
               call:    LD      B,0
                        LD      DE,BUFFER ;256*8 bytds
               READ     CALL    4AC1H     ;read sector
                        LD      L,0
                        PUSH    BC
                        LD      BB,256
                        LDIR
                        POP     BC
                        INC     B
                        LD      A,B
                        CP      8
                        JR      NZ,READ
                        RET

LEVEL II/DOS RAM MAP

4001-4014      Jump vectors for RST 8 - RST 56
4015-401C      Keyboard Device Control Block (DCB)
401D-4024      Video display DCB
4025-402C      Line printer DCB
4036-403C      Work area for keyboard input routine
403D           Print size flag: 0=64 char., 8=32 char.
403E           OSVER$- DOS version #
4040           25 millisecond clock count
4041-4043      TIME$, time of day: seconds, minutes, hours
4044-4046      DATE$- day of year: year, day, month
4049-404A      HIFH$- highest unused RAM address (DOS)
408E-408F      (L2 only) Entry point to USR routines
4093-4098      Input and output port routines
4099           INKEY$ storage of key pressed
409A           Error code for RESUME
409B           Printer carriage position
409C           Device type flag: -1=tape, 0=video,  1=line printer
409D           Used by PRINT#
40A0-40A1      Pointer to lowest address available for string storage
40A2-40A3      program line number counter (current line # being
               processed)
40A4-40A5      Start of BASIC program pointer.  Normal values for: (L2)=42E9;
               (Disk BASIC)=varies with version of  DOS/BASIC.
40A6           Line cursor position, used for TAB
40A7-40A8      Input buffer pointer
40AA-40AC      Seed for RND
40AF           Number type flag (NTF): 2=int, 3=stng, 4=sngl, 8=dbl
40B1-40B2      Pointer to highest address available for string storage
               (set by MEMORY SIZE).  Protected memory, if any, follows.
40B3-40B4      String work area pointer
40B5-40D5      String work area
40D6-40D7      Pointer to next byte of string storage
40D8-40D9      Present byte count pointer
40DA-40DB      Last DATA,READ line #
40DC           Used by DIM
40DE           Used by PRINT USING
40DF-40E0      Entry point storage for SYSTEM tapes (accessed by "/"
               command)
40E1           AUTO flag (0=off)
40E2-40E3      Current line #
40E4           AUTO increment size
40E6-40E7      Encoded statement pointer
40E8-40E9      Stack pointer pointer
40EA           Used during RESUME
40EC-40ED      EDIT line #
40EE           Used during RESUME
40F0-40F1      ON ERROR location for ON ERROR GOTO
40F5-40F6      Last line # executed prior to a BREAK
40F7-40F8      Last statement byte counter for CONTINUE retrieval
40F9-40FA      Start simple variables pointer (top of BASIC program plus
               1)
40FB-40FC      Start of arrays pointer (end of simple variables)
40FD-40FE      Start of free space pointer (end of arrays)
40FF-4100      DATA pointer
4101-411B      Variable type declaration table for each letter: 2=int,
               3=stng, 4=sngl, 8=dbl
411B           TRON flag: 0=off (TROFF), 175=on (TRON)
411D-4124      Arithmetic accumulator
4127-412E      Hex arithmetic accumulator
4130-4131      Line # work area pointer
4152-41A6      DOS entry points
41BE-41C0      (L2 only( Jumps here on RESET button hit.  You can put your
               own 3 byte instrtction here to jump to your own routine.
41E8-42E8      Input buffer area
               (stack pointer for system is at 4288 )
4200-51FF      TRSDOS
42E9           Start of user RAM for program storage
4318-4357      DOS command buffer- Last DOS command entered (64 chars.).
4500-4517      DOS interrupt table contains address pairs for interrupt
               routines (ie. CLOCK, TRACE, etc.).  You can place your own
               routine addresses in this table.  An example is below:
                        DI                ;disable interrupts
                        LD      HL,4510H  ;address of table link
                        LD      (HL),MYROUT ;address of my interrupt
               routine
                        EI                ;enable interrupts
5200-6FFF      Disk BASIC or DOS utilities when loaded, or user memory
57F0           61 character ASCII copyright notice (DOS)

DISK BASIC COMMAND VECTORS

Address	Command
4152	CVI
4155	FN*
4158	CVS
415B	DEF
415E	CVD
4161	EOF
4164	LOC
4167	LOF
416A	MKI$
416D	MKS$
4170	MKD$
4173	CMD
4176	TIME$*
4179	OPEN
417C	FIELD
417F	GET
4182	PUT
4185	CLOSE
4188	LOAD
418B	MERGE
418E	NAME
4191	KILL
4194	&*
4197	LSET
419A	RSET
419D	INSTR*
41A0	SAVE
41A3	LINE
* Items marked with an asterisk are called during expression evaluation.

TRS-80 MODEL 1/3 KEYBOARD PEEK TABLE

                      ----- Decimal Contents ----,
Address   1     2     4     8     16     32     64     128    Hex Address
------- ----- ---,- ----- ----- -----  -----  -----   -----   -----------
14337     @     A     B     C      D      E      F      G        3801       1
14338     H     I     J     K      L      M      N      O        3802       2
14340     P     Q     R     S      T      U      V      W        3804       4
14344     X     Y     Z     ,      -      -      -      -        3808       8
14352     0     1     2     3      4      5      6      7        3810      16
14368     8     9    *:    +;     <,     =-     >.     ?/        3820      32
14400  enter  clear break  up    down   left  right  space       3840      64
14464  shift    -     -     -  control    -      -      -        3880     128
---,--- ----- ----- ----- ----- -----  -----  -----   -----           ------,--
          0     2      4    8     10     20     40      80             14336
                      -----   Hex Contents   -----

Notes on the table:

1.  Blank areas ("-") of the table are not used on the standard TRS-80.
2.  The control key at location 14464 is used by the ELECTRIC PENCIL.
3.  The break key can not be used in BASIC programs, but can be checked in
machine language programs.
4.  In BASIC use  -  variable = PEEK(address)
      ie:    IF PEEK(14400)=8 THEN SET(X+1,Y)  ' up arrow key was pressed
5.  In machine language you can use- LD A,(3840H) ;08H = up arrow
6.  If two or more keys are pressed at the same time you will get the sum of
the keys.
7.  You can also combine more than one address.  Note the right-hand column
of numbers.  If you total this number with other row numbers you want to
address, and add 14436, you will get the final decimal address to PEEK.
8   In BASIC a better way to use this table, than described in 4 above, might
be to
    PEEK(address) AND (value to check)  -  This will recognize a key as being
pressed
    even when other keys are being held down.

Try running this small program and hold down more than one ARROW key at the
same time.

                 5 DEFINT A
                10 A = PEEK(14400)
                20 IF (A AND 8 ) THEN PRINT "UP ":
                30 IF (A AND 16) THEN PRINT "DOWN ";
                40 IF (A AND 32) THEN PRINT "LEFT ";
                50 IF (A AND 64) THEN PRINT "RIGHT ";
                60 IF (A AND 255)THEN PRINT
                70 GOTO 10

TRS-80 MODEL 4 KEYBOARD PEEK TABLE - Colin Dunn

In order to be able to PEEK these keyboard keys, you must first:

(a)	If using BASIC: set HIMEM to F3FFH, and POKE location 120 with 134, and also do an OUT 132,134.

(b)	If you're using machine language: Disable the interrupts (DI), and then perform an OUT to port 132 with 134.

The above will make the keyboard and screen memory accessible. To reversethis condition, use:

(a)	In BASIC: POKE 120,135:OUT 132,135. This will make normal RAM accessible and cancel out the use of keyboard and video memory.

(b)	In machine language: Out to port 132 with a 135. Also, re-enable the interrupts to keep the type-ahead and real-time clock and any other interrupt task active.

If you program the keyboard and screen access in machine language, place no programs higher than location F3FFH. If you do, the video RAM will load over the program, and any attempts to jump, call, or use data in addresses above F3FFH will fail. JUMPs and CALLs will crash the SYSTEM!!!

This list of keyboard locations and values was compiled by Colin Dunn. This list will be useful for programmers looking to access the keyboard memory directly and write programs like keyboard drivers, games, etc.

Example: A=peek(&HF440) is the same in 4 mode as A=peek(14400) in the 3 mode.

Location 1 2 4 8 16 32 64 128 ------------------------------------------------------------------------------- F401H [@] [A] [B] [C] [D] [E] [F] [G] F402H [H] [I] [J] [K] [L] [M] [N] [O] F404H [P] [Q] [R] [S] [T] [U] [V] [W] F408H [X] [Y] [Z] [ NOT ASSIGNED ] F410H [0] [1] [2] [3] [4] [5] [6] [7] F420H [8] [9] [:],[*] [N/A] [,],[<] [-],[=] [.],[>] [/],[?] F440H [ENTER] [CLEAR] [BREAK] [UPARW] [DNARW] [<-] [->] [SPACE] F480H [LSHFT] [RSHFT] [CTRL] [CAPS] [F1] [F2] [F3] [N/A] --------------------------------------------------------------------------

Directly Access Model 4 Video - Colin Dunn

If you are frustrated on the Model 4 because you can't directly access video memory, there is relief for you!!! You can do some spectacular video tricks in the 3 or 4 mode.

A.	Model 3 mode

	The 3 mode uses 1024 bytes of video memory addressed from locations 15360 to 16383. If you're running on a model 4, you can have TWO pages of video RAM in 3 mode. This is useful for page-flipping animation or fast screen displays. I have used it to hide DOS messages when I want to make a pseudo-self-booting disk (contains DOS, but has no notice of the DOS)

	That's enough background, so I'll get on with the explaining of Mod 3 mode video access!!

	OUT 132,0 - Sets video access to page 1. Page 1 does not have to be on the screen to access it.

	OUT 132,128 - Sets video access to page 2. Same rules apply. (NOTE: Page 2 might have garbage in it from use of the 4 mode or from turning on the computer. Execute a CLS command to clear page 2.)

	OUT 132,4 - Sets video access to page 1 in 80 X 24 mode. With this setup, you can only print on the upper half of the screen.

	OUT 132,132 - Sets video access to page 2 in 80 X 24 mode. With this setup, print only appears on the lower half of the screen.

	(This is how those 80X24 drivers for the 3 mode work. Printing at position 64 will be in the middle of the first line, so each line of screen is 80 print positions apart.)

	OUT 136,12:OUT 137,0 - Displays page 1 on the 64X16 mode. You can write to page 2, but you won't see it.

	OUT 136,12:OUT 137,4 - Displays page 2 on the 64X16 mode. You can write to page 1, but you won't see it unless page 1 is on the screen.

	OUT 132,8 - sets up page 1, 64X16, with INVERSE VIDEO replacing the graphic characters. OUT 132,12 will do the same for 80X24.

	OUT 132,140 - sets up page 2 on the 64X16 screen with the inverse video. If you use OUT 132,144, you'll be writing to the bottom of the 80X24 screen with the inverse video characters.

	(Note: to go back to graphic characters, use OUT 132,0 or OUT 132,128 )

B.	Model 4 Mode

	You can do the direct screen poke trick in 4 mode. If you hated the pains of page switching in the 3 mode to use 80X24 access, the 4 mode can help you.

	You MUST first execute a CLEAR,&HF3FF command before doing any of this!! If you don't, the computer will crash!!!!

	Now that you've set aside all that memory, you can start working on it. If you like to set up SYSRES modules, set the HIMEM pointer to &HF3FF first before loading SYS modules into memory. It is fatal to possibly overwrite them. I have not really tried SYSRES modules and direct screen access. I will post a message in the Model 4 Corner of the TBBS ISLAND when I get around to testing it.

	Enough of those warnings!!! Here goes...

	POKE 120,134:OUT 132,134 - This sequence sets up video memory at F800H and keyboard memory at F400H. I do not know the key combos - experiment with the keyboard memory to find out!

	POKE 120,135:OUT 132,135 - This sequence switches video and keyboard memory out and programs return to those locations. It is not advisable to do DOS operations if video memory is resident!!!

	If you are using assembly language, don't put data in address 120 decimal. You just load the A register with 134 and OUT (132),A to switch in video memory. YOU MUST DISABLE INTERRUPTS OR DOS SERVICE ROUTINES WILL STEAL THE VIDEO MEMORY OUT FROM UNDER YOUR PROGRAM!!!!!!!

DISK SPEEDUP CHART

----------I-------------------------------
          I       Delay in miliseconds
Command   I     40      20      10      05
----------I-----------------,,------------
RESTORE   I     0B      0A      09      08
----------I-------------------------------
SEEK      I     1B      1A      19      08
----------I-------------------------------

Program   I     DOS     Trk. Sec.  Byte  Org.  Ndw   Command
----------I-------------------------------------------,-----
BOOT/SYS  I     ALL*    0    0     B9    361B  3618  SEEK    (except NEWDOS 80)
          I     NEWDOS  0    0     6A    361B  3618  SEEK    (only   NEWDOS 80)
          I     80.1    0    0     A5    360B  3608  RESTORE  "       "     "
------,--------------------------------------------,--------
          I     TRSDOS  0    7     51    3E1B  3E18  SEEK
          I     (ALL)   0    7     C4    3E0B  3E08  RESTORE
          I     ----------,---------------------------------
          I     NEWDOS  0    7     0E    3E0B  3E08  RESTORE
SYS0/SYS  I      2.1    0    9     0E    3E1B  3E18  SEEK
          H     -------------------------------------,------
          I     NEWDOS  0    8     CC    3E0B  3E08  RESTORE
          I     80.1    0    8     FD    3E1B  3E18  SEEK
          I     --,-----------------------------------------
          I     VTOS    0    7     15    3E1B  3E18  SEEK
          I      3.0    0    7     90    3E0B  3E08  RESTORE
----------I----------------------------------,---------,----

Note:   The values under the "new" column are for 5 milisecond operation.
        For 20 ms. change 18 to 1A, 08 to 0A.

        - older Shugarts & some newer ones use 40 ms.
        - some newer Shugarts can use 40 or 20 ms.
        - Micropolis uses 40 ms.
        - Pertecs can use 40 or 20 ms.
        - MPIs and Siemens can use 40, 20, 10, or 5 ms.

SYSTEM TAPE FORMAT

TAPE LEADER             256 zeroes followed by a A5 (sync byte)
55                      header byte indicating system format
xx xx xx xx xx xx       6 character file name in ASCII

        3C              data header
        xx              length of data 01-FFH, 00=256 bytes
        lsb,msb         load address
        xx ... xx       data (your program)
        xx              checksum of your data & load address

        .               repeat from 3C through checksum
        .
        .
78                      end of file marker
lsb,msb                 entry point address

EDITOR/ASSEMBLER SOURCE TAPE FORMAT

TAPE LEADER             256 zeroes followed by a A5 (sync byte)
D3                      header byte indicating source format
xx xx xx xx xx xx       6 character file name in ASCII

        xx xx xx xx xx  line # in ASCII with bit 7 set in each byte
        20              data header
        xx ... xx       source line (128 byte maximum)
        0D              end of line marker

        .
        .
        .

1A                      end of file marker

BASIC TAPE FORMAT

LEADER                  256 zeroes followed by an A5 (sync byte)
D3 D3 D3                BASIC header bytes
xx                      1 character file name in ASCII

        lsb,msb         address pointer to next line
        lsb,msb         line #
        xx ... xx       BASIC line (compressed)
        00              end of line marker

        .
        .
        .

00 00                   end of file markers

VIDTEX ESCAPE SEQUENCES - Neil Morrison

VIDTEX lets the host computer perform screen control functions through escape sequences. Remember that these are remote functions executed by the host and cannot be performed from the keyboard. The following table summarizes the screen control sequences and the functions they perform. Note the difference between lower and uppercase.
Escape Control Sequence Summary:
Sequence	Function
{ESC}{ESC}O	Open RAM buffer
{ESC}{ESC}C	Close RAM buffer
{ESC}{ESC}Z	Zero RAM buffer
{ESC}A	Cursor up
{ESC}B	Cursor down
{ESC}C	Cursor right
(ESC)D	Cursor left
{ESC}G4	Semi-graphics 4 mode
{ESC}GN	Text mode
{ESC}H	Home cursor
{ESC}J	Clear to end of page
{ESC}K	Clear to end of line
{ESC}Y line col	Position cursor
{ESC}b	Lock keyboard
{ESC}c	Unlock keyboard
(ESC}e	Disable display
{ESC}f	Enable display
{ESC}g	Restart VIDTEX
{ESC}j	Clear Page
{ESC}l	Normal character width
{ESC}m	Wide character width
{DC1}	XON
{DC2}	Printer on
{DC3}	XOFF
{DC4}	Printer off
Graphics Mode:
	An {ESC}G4 is used by the host to specify semi-graphics 2 x 2 mode. These codes are used internally by the Videotex Plus software and cannot be generated from the keyboard. In this mode the parity bit is used to distinguish between graphic and ASCII characters. If the parity bit is zero, the character is a standard ASCII character. If the parity bit is one, the character is a graphics character.
Model II Videotex Plus does not support graphics or color. When graphics mode is required by the host. similar Model II graphics characters are substituted for the graphics codes. These are not true representations of Videotex’s standard graphics.

Cassette Recorder Levels - Neil Morrison

Recorder Model	User-Generated Tapes			Pre-Recorded Radio Shack Tapes
	Model I		Model III	Model I		Model III
	Level I	Level II		Level I	Level II
CTR-40	Yellow Line	Red Line		Yellow Line	Red Line
CTR-41	6-8	4-6		6.5-8.5	5-7
CTR-80	4.5-6.5	3-5	5-7	5.5-7.5	2.5-5	4-6
CTR-80A	4.5-6.5	3-5	5-7	5.5-7.5	2.5-5	4-6
CTR-81	4.5-6.5	3-5	5-7	5.5-7.5	2.5-5	4-6

Entry points to various Level II BASIC ROM routines

Entry points to various Level II BASIC ROM routines which may be accessed by user programs.

Keyboard routines

KBD1       2BH         INKEY$ CALL
KBD2       358H        SAVE DE REGS, THEN CALL 2B
KBWT1      49H         KBD INPUT WITH WAIT
KBWT2      384H        KBD INPUT WITH WAIT, DE SAVED
LINP1      5D9H        LINE INPUT ROUTINE
                        ENTER WITH:
                           HL => STORAGE ADDRESS
                           B  => MAX LENGTH TO INPUT
LINP2      361H        LINE INPUT ROUTINE 2
INPUT      1BB3H       SAME AS LINP2, BUT WITH "?"
LBUFF      40A7H       STORAGE BUFFER ADDRESS FOR LINP2

Display routines

DSP1       33H         Display byte at cursor pos
CLS        1C9H        Clear screen
BLINK      22CH        Blink "*" in right upper corner
DSP2       33AH        SAVES DE AND CALLS DSP1
DSTR       28A7H       DISPL STRING POINTED TO IN HL
SETRES     150H        ENTRY TO SET/RESET ROUTINES
CURSOR     4020H       CURSOR POSITION

Miscellaneous routines & addresses

BASIC      1A19H       RETURN POINT FOR BASIC
DOS        402DH       RETURN POINT FOR DOS
DOSERR     4030H       RETURN TO DOS WITH ERROR
CHLDE      1C90H       COMPARE HL WITH DE
FETCH      1D78        FETCH NEXT NON-BLANK CHARACTER
                        FOLLOWING THAT IN HL
DECBIN     1E5AH       DECIMAL # => BINARY
        RST 10H         INCREMENTS HL, LOADS (HL)=> A,
                        & SETS CARRY FLAG
WLDR       284H        WRITES LEADER ON CASSETTE TAPE
WBYTE      264H        WRITES ONE BYTE TO TAPE
COFF       1F8H        TURNS OFF CASSETTE MOTOR
RLDR       293H        READS SYNC BYTE FROM CASSETTE
RBYTE      235H        READS ONE BYTE FROM TAPE

Floating-point arithmetic routines

TYPE FLAG IS 40AFH; VALUES AS FOLLOWS:
        2 - INTEGER
        3 - STRING
        4 - SINGLE PRECISION FLOATING POINT
        8 - DOUBLE PRECISION FLOATING POINT

FLOATING POINT ACCUMULATORS (FPACC) AS FOLLOWS:
        INTEGER: 4121H - 4122H
        STRING:  4121H - 4122H HOLDS DESCRIPTOR ADDRESS
SINGLE PRECISION: 4121H - 4124H (4124 IS EXPONENT)
DOUBLE PRECISION: 411DH - 4124H (4124 IS EXPONENT)

OPERAND LOCATIONS AS FOLLOWS:
         INTEGER:  REGISTER PAIRS DE & HL
SINGLE PRECISION:  REGISTER PAIRS DE & HL
DOUBLE PRECISION:  4127H - 412EH

TSTYP      25D9H       TEST TYPE FLAG AT 40AF
DSTOR       9B4H        STORE SNG-PRC VAL IN DE:BC IN
                        FPACC
SLOAD       9C2H        LOAD SNG-PRC INTO DE:BC FROM
                        ADDRESS IN HL
SCOPY       9B1H        COPY SNG-PRC FROM HL ADDR TO
                        FPACC
SGET      9BFH        LOAD FPACC INTO DE:BC
SSTAK     9A4H        PUSH FPACC INTO STACK (DE BC)
ISTOR      0A9AH       STORE INT IN FPACC & SET TYPE
ASTOR      0E6CH       STORE NUMERIC STRING IN FPACC
NEDIT      0FBDH       NON-FORMATTED NUMERIC EDIT
FEDIT      0FBEH       FORMATTED NUMERIC EDIT
CSVEC      2865H       CREATE STRING VECTOR
FPACC      4121H       FLOATING POINT ACCUMULATOR
DFPACC     411DH       DOUBLE-PRECISION FPACC
DOPER      4127        DOUBLE-PRECISION OPERAND REGS

Arithmetic function routines

IADD       0BD2H       INTEGER ADD DE+HL =>FPACC
ISUB       0BC7H       INTEGER SUBTRACT DE-HL=>FPACC
IMUL       0BF2H       INTEGER MULTIPLY DE*HL=>FPACC
IDIV       2490H       INTEGER DIVIDE DE/HL =>FPACC
SADD       716H        SNGPRC ADD OPER+FPACC=>FPACC
SSUB       713H        SNG SUBTRACT OPER-FPACC=>FPACC
SMUL       847H        SNG MULTIPLY OPER*FPACC
SDIV       8A2H        SNG DIVIDE OPER/FPACC
DADD       0C77H       DBL PREC OPER+FPACC
DSUB       0C70H       DBL PREC SUBTRACT OPER-FPACC
DMUL       0DA1H       DBL PREC OPER*FPACC
DDIV       0DE5        DBL PREC OPER/FPACC
SGN        98AH        FPACC = SGN(FPACC)
INT        0B37H       FPACC = INT(FPACC)
ABS        977H        FPACC = ABS(FPACC)
SQRT       13E7H       FPACC = SQRT(FPACC)
RNDM       14C9        FPACC = RND(FPACC)
LOG        809H        FPACC = LOG(FPACC)
EXP        1439H       FPACC = EXP(FPACC)
COSN       1541H       FPACC = COS(FPACC)
SINE       1547H       FPACC = SIN(FPACC)
TAN        15A8H       FPACC = TAN(FPACC)
ATAN       15BDH       FPACC = ATAN(FPACC)
CINT       0A7FH       FPACC = CINT(FPACC)
CSNG       0AB1H       FPACC = CSNG(FPACC)
CDBL       0ADBH       FPACC = CDBL(FPACC)
FIX        0B26H       FPACC = FIX(FPACC)

DEC ADDR       HEX ADDR        FUNCTION
  14305           37E1          0, FOR BETTER DISK SAVES
  16405           4015          1 =KEYBOARD ON
                                2 =KEYBOARD OFF
  16413           401D          1 =DISPLAY OFF
                                7 =DISPLAY ON
  16414           401E          141 =DISPLAY TO PRINTER
                                88 =RESTORE DISPLAY
  16415           401F          5, 4 =???
  16449           4041          CLOCK REGISTER, SECONDS
  16450           4042          CLOCK REGISTER, MINUTES
  16451           4043          CLOCK REGISTER, HOURS
  16452           4044          CLOCK REGISTER, YEAR
  16453           4045          CLOCK REGISTER, DAY
  16454           4046          CLOCK REGISTER, MONTH
  16553           404F          255 =DATA READ AFTER CASS INP

  14312           37E8        >127 =LINEPRINTER NOT READY
  15339           3BFF         CHECK IF KEY HELD DOWN
  16457           4049  TOP-OF-MEMORY (DOS MAIN SYSTEM)
                              DISK BASIC HOLDS VALUE-1 IN
                               40B1.
                40A0-40A1 IS THE POINTER TO THE
                STRING STORAGE AREA (IE., IF YOU
                "CLEAR 50" THESE ADDRESSES WILL
                HOLD THE VALUE IN 40B1-40B2 MINUS
                50). ALWAYS STORED LSB/MSB.

KEYBOARD VALUES
                                VALUES
ADDR    1     2     4     8     16    32    64    128
15105    @     A     B     C      D     E     F     G
15106    H     I     J     K      L     M     N     O
15108    P     Q     R     S      T     U     V     W
15112    X     Y     Z
15120    0     1     2     3      4     5     6     7
15136    8     9     :     ;      ,     -          /
15168   ENTER  CLS   BRK    LF     LA     RA     SPACE
15232   SHIFT

 LF = LINEFEED   LA = LEFT ARROW   RA = RIGHT ARROW
 CLS = CLEAR KEY   BRK = BREAK

Model 4P boot mode key selection

Model 4P boot mode key selection (hold key till completed):

no keys pressed - boots in III mode if MODELA/III on disk 0
F1      pressed - boots from hard disk
F2      pressed - boots from floppy disk
F3      pressed - boots in III mode if MODELA/III on disk
L       pressed - re-load ROM image (in case of damage)
N       pressed - boots TRSDOS 6.x (not III's 1.3)
P       pressed - prompts to switch disks after loading III ROM
        (press <BREAK> to run III Basic or <ENTER> to load & run a DOS
V       pressed - prints ROM version on screen
.       pressed - performs dynamic RAM test until <RESET> is presed
<SHIFT><BREAK> - boots from RS232. Acts like Network III Boot ROM

Model 4P Modem Commands

Commands:

	*	Opens modem for programming.
	A	Switches modem to the answer mode.
	@	Stand by to receive a new Abort code.
	C	Clears (resets) modem memory.
	D	Clears current telephone number from memory. Must precede any new telephone number.
	E	Toggle the Echo enable switch.
	F	Fast Rotary or Tone dialing (20 pps.)
	G	Toggle forced carrier detect switch.
	L	Transmits (displays) current contents of modem memory to the computer (terminal).
	M	Toggles the Manual/Automatic switch.
	O	Switches the modem to the Originate mode.
	P	Inserts a 3 second pause in dialing sequence.
	Q	Puts modem into LOCal Test Mode.
	R	Rotary dialing (default value).
	S	Slow Rotary or Tone dialing (10 pps.) (default value).
	T	Tone dialing (10 digits per second).
	X	Executes current program (dials phone number in memory, goes into Self-Test mode, waits for telephone to ring while in answer mode).
	BKSP	Erase the last code entered when programming dialing information.
	,	Insert a user space when programming dialing information.

Examples

To see the menu (or list) of the modem you type: *L in the terminal program such as COMM/CMD, XT4/CMD, etc.
To program it in order to call 555-3595, you would do the following on one line:
**C**MOGFDR652-3595;
     C clears modem
     M changes to automatic
     O is for originate
     G disables forced carrier detect
     F is for Fast dialing
     D is for dialing
     R is for Rotary
Now if you typed the modem will respond with:
     MODE=A
     TYPE=O
     F CD=N
     TEST=N
     NUMB=R652-3595
     RATE=F
     EXIT=14
then you would type to execute the above commands and dial the number.

Model 4 Graphics Board - Undocumented Ports

Programming the Hi-Res Board

- Paul Bradshaw

============================

There are 3 undocumented ports usable with the Model 4 Graphics Board. They are ports 140, 141 and 142. They control such various functions as enabling the mixed text/graphics mode, and controlling X,Y scrolling around the entire 32K of graphics memory (of which only 18.75K is actually displayed and used at the current time). First a discussion of the documented ports and their use; ports 128, 129, 130 and 131.

Ports 128 and 129 are the x and y address ports, respectively. They select the byte on the graphics board to be read or written to. They do NOT select an individual point, but an entire byte of data out of the 32K of memory on the graphics board. The y address may vary from 0 to 255 (with 0 to 239 being displayable via BASICG - more later) and the x address may vary from 0 to 127 (with 0 to 79 displayable - again, more later). This enables you to examine the entire bank of graphics RAM ( 128x256 = 32K ).

To read or write the byte selected, use port 130. The Basic statements A=INP(130) and OUT 130,A will read and write to that byte, respectively. The data shows up on the graphics screen as the bit image of the byte. This is the binary representation of the byte you send. E.G. - if you OUT the number 5 to port 130, it would "set" two points on the screen, because 5 is representated by "setting" bits 0 and 1 of a byte. Refer to your TRSDOS manual for a discussion of bits, bytes, and binary.

This is a routine that will, in Basic, set any point on the screen: This is not a complete Basic routine, but can be used in a subroutine. No error checking is done.

10 REM X & Y HOLD THE X,Y COORDINATES OF THE POINT (X=0-639,Y=0-239)
20 OUT 128, X\8             '** SELECT X COORDINATE
30 OUT 129, Y               '** SELECT Y COORDINATE
40 T=INP(130)               '** GET DATA ALREADY THERE
50 OUT 130, T OR 2^(7-(X MOD 8 ))   '** MERGE REQUESTED BIT AND DISPLAY
60 RETURN                   '** RETURN FROM SUBROUTINE

Line 20 outputs the requested x coordinate dividided by 8. This is because there are 8 bits in a byte, and the port selects a whole byte (8 "X" Pixels) Line 30 outputs the requested y coordinate directly to the board. No conversion is necessary

Line 40 gets what ever is already displayed at that point, and saves it.

Line 50 is the only complicated part: It takes what ever was already displayed at that point (saved in T) and "or's" it with the point you selected. (Please refer to your TRSDOS/BASIC manual for details on "or"-ing.). The equation is best explained part by part. The (X MOD 8 ) finds the remainder of the x address divided by 8 (remember we found the byte by using the quotient of x divided by 8 ). We then subtract this value from 7, and raise 2 to this number. Why? Because of the way the pixels are mapped. if we were to out put a 1 to port 130, to x,y address (port addresses) 0,0 - we would get 0 0 0 0 0 0 0 1 displayed (zero's standing for no point lit, a 1 standing for a "set" point) This is not what we want. We want 1 0 0 0 0 0 0 0

So, we take the remainder of x/8 - [ in our example of trying to set point 0,0 on the screen, a 0 would be output to 128 (0/8 ), and a 0 would be output to 129 (directly) ] - which is 0. Subtracting this number from 7 gives us 7. Raising two to this power yields 128 (2^7=128 ), which is what we want (a byte of "1 0 0 0 0 0 0 0" )!!

Port 131 controls various aspects of the graphics board - the bits are mapped as follows:

Bit #    Description
=====    ============
  0   -  Turns the Graphics screen on and off: 1 = ON, 0 = OFF
  1   -  Controlls Video Waits:  1 = Wait, 0 = NO WAIT
  2   -  X "Clocking" Control:  1 = DECREMENT, 0 = INCREMENT
  3   -  Y "Clocking" Control:  1 = DECREMENT, 0 = INCREMENT
  4   -  X "Clocking" Control:  0 = CLOCK AFTER READ, 1 = NO CLOCKING
  5   -  Y "Clocking" Control:  0 = CLOCK AFTER READ, 1 = NO CLOCKING
  6   -  X "Clocking" Control:  0 = CLOCK AFTER WRITE, 1 = NO CLOCKING
  7   -  Y "Clocking" Control:  0 = CLOCK AFTER WRITE, 1 = NO CLOCKING

Address clocking is a very valuable feature, and greatly speeds up graphics programs. Basicly it consists of this - you can program the graphics board to AUTOMATICALLY alter the x,y address so that you need not constantly be updating them with out's to ports 128 and 129. This cuts the number of commands needed to perform a function, and thus speeds up processing by a factor of almost three! Here is an example in Basic:

We wish to "invert" the screen - make white points black, and black points white. We will need to read a byte from the graphics board, invert it, write it back out, and continue with the next byte. Thus we will need to ADD one to the y position after every WRITE. We don't want the x coordinate to do anything, we want the graphics screen displayed, and video waits on (why later) Thus the status byte we need is:

  Bit position#  7 6 5 4 3 2 1 0
  Byte we need:  0 1 1 1 0 1 1 1

Understand why before you go on. This byte is 119 (2^6+2^5+2^4+2^2+2^1+2^0) decimal. So now we have all we need for our program.

10 OUT 131,119           '** SELECT FUNCTIONS WE NEED FROM STATUS REGISTER
20 FOR X=0 TO 79         '** X COORDINATE GOES FROM 0 TO 79 (BYTES, REMEMBER?)
30 OUT 128,X             '** SELECT X COORDINATE
40 OUT 129,0             '** Y COORDINATE STARTS AT ZERO
50 FOR N=0 TO 239        '** NUMBER OF BYTES (Y COORDINATES DOWN THE SCREEN)
60 T=INP(130)            '** GET BYTE TO REVERSE
70 OUT 130,(NOT T)AND 255'** OUTPUT REVERSED BIT IMAGE, SELECT NEXT BYTE
80 NEXT N                '** CONTINUE UNTIL END OF "ROW" (240 BYTES)
90 NEXT X                '** SELECT NEXT X ADDRESS

Ignore the (NOT T) AND 255 if you don't understand how it "reverses" the bits (complements them). It does. The main point is that nowhere in the main loop (lines 50-80) did you have to output an X or Y address. Each new Y address was computed AUTOMATICALLY. Just like if you had written:

20 FOR X=0 TO 79         '** X GOES FROM 0 TO 79 BYTES
25 FOR Y=0 TO 239        '** Y GOES FROM 0 TO 239
30 OUT 128,X             '** SELECT X ADDRESS
40 OUT 129,Y             '** SELECT Y ADDRESS
60 T=INP(130)            '** GET BYTE TO COMPLEMENT
70 OUT 130,(NOT T)AND 255'** "REVERSE" IT
80 NEXT Y                '** CONTINUE WITH NEXT Y ADDRESS
90 NEXT X                '** CONTUNUE WITH NEXT X ADDRESS

They may look equally long, but the first only has two statements inside the main loop, while the second has four. The time spent adds up fast.

Only one thing can access memory at one time. The Graphics Memory is trying to be accessed by TWO things all the time. Your routine making graphic designs and the Video Scanner, which is trying to display them on the screen. If you were to have the two happen at the same time (your routine getting the right of way), then the Video Scanner would have nothing to display. But the electron gun in your screen never stopps - if it has no data to tell it what to do, it sends "white". So, every time your routine is accessing graphics memory, it is forced to wait until the Scanner it finished with a "line". This slows down your routine. These waits are called Video Waits. They can be enabled or disabled (bit 1 of the status register, port 131). Disableing them increases the speed of your routine (because it doesn't have to wait), but at the price of a "snowy" screen. To demonstrate the speed advantage, I wrote a "clear screen routine". With waits enabled, it took about one second to clear the entire graphics screen. With them disables - it took less than 3/10th of a second!!

UNDOCUMENTED PORTS

==================

Ports 140 and 141 control X and Y scrolling of the displayed graphics memory. This enables you to draw BEYOND the limits of the screen (port addreses x=0 to 79 and Y=0 to 239 are limits under basic. Port addreses X=0 to 127 and Y=0 to 255 are usable and perfectly legal), and then scroll over to view them. The video screen acts as a window to a larger drawing area (a 640x240 window to a 1024x256 drawing area). These two ports control which portion of the larger area you see.

The way they work is this: The number that is output to this port is a reference to the port address that will be the "zero reference" for the video screen. That sounds very complex, but this VERY easy to use. Say you output the number 10 to port 140 (the X scrolling port). The screen shifts to the left 10 units (80 pixels). If you then output an 11, the screen shifts over 1 more unit (8 pixels). The number output is absolute, not relative to what was previously output. Think of numbering the columns of x bytes (columns 0 thru 79) - the number output moves that column over to the "zero" position (the left edge of the screen for X, the top of the screen for Y). BASICG does NOT recognize the extra memory. EVEN IF you scroll the screen over, all Basicg commands still work with the old area (some of which has now moved out of view). Basicg also does not clear this extra memory, so when you scroll, garbage will come into view. Here is a program that moves a shape around the screen:

10 CLR:SCREEN:CLS                           '** INITIALIZE SCREEN
20 CIRCLE(320,120),100:CIRCLE(320,120),200  '** DRAW "DOUGHNUT"
30 PAINT (320,120),60                       '** FILL IT
40 FOR X=0 TO 127                           '** PREPARE TO SCROLL  HORZ
50 OUT 140,X                                '** SCROLL IT
60 FOR T=0 TO 10:NEXT T                     '** PAUSE FOR A WHILE
70 NEXT X                                   '** CONTINUE
80 FOR Y=0 TO 255                           '** PREPARE TO SCROLL VERT
90 OUT 141,Y                                '** SCROLL IT
95 FOR T=0 TO 5:NEXT T                      '** PAUSE FOR A WHILE
100 NEXT Y                                  '** CONTINUE
110 OUT 140,0:OUT 141,0                     '** PUT SCREEN BACK TO NORMAL

Watch this program run, and you will get a better idea of how these functions work. Remember, they do NOT affect the way the ports 128 & 129 address the graphics board - they only affect the way the graphics memory is displayed!

The last port I will discuss is port 142. This port enables a mixed Text and Graphics mode. All graphics and text are visible on the same screen at the same time (in direct contradiction to the manual)! Where text and graphics overlap - the point is reversed. If something is printed over a block of white then that printing appears in "reverse video". In fact, this is the only way to get reverse video when this mode is active. All characters are displayable but reverse video characters will appear as normal ones.

To enable this mode, perform an OUT 142,1. To go back to normal, perform an OUT 142,0. Note: the mixed text/graphics mode is only available when the graphics screen is selected (Basicg SCREEN 0, or OUT 131,1). This enables you to have text only, graphics only, and mixed text and graphics modes!! I will conclude this discussion with a short program that demonstrates all three of these undocumented ports:

10 CLR:OUT 142,1:SCREEN 0:PRINT CHR$(21);
20 CIRCLE(320,120),100:CIRCLE(320,120),200:PAINT(320,60),1,1
30 PRINT "This is a test of the undocumented ports on the Radio Shack"
40 PRINT@(10,25),"HIGH-RESOLUTION GRAPHICS BOARD";
50 PRINT@(19,0),;
60 FOR N=0 TO 255:PRINT CHR$(0);CHR$(N);:NEXT N
70 T=0:FOR X=0 TO 127
80 OUT 140,X:OUT 141,(ABS(SIN(T))*120+240)MOD 256:T=T+.1
90 NEXT Y,X:GOTO 70

When doing machine language programs, using the OTIR,OTDR,INIR, and INDR commands in union with address clocking speeds things up considerably. Also turn video waits OFF whenever practical (the graphics screen isn't being displayed at the moment, etc...)

ADDITIONAL INFORMATION

==================

O.K. - The graphics board has all these neat features. But I can't use them from within basicg (easily). Big deal, right? RIGHT! Because using these features is very easy, given a simple little subroutine to set things all up. You CAN make basicg recognize all that extra memory, and you CAN write basicg programs that draw with 1024x256 graphics! All you must do, is convince Basicg not to "throw away" the values of x between 640 and 1023. The same for the y values between 240 and 255. This is how you do it:

While doing a little detective work poking around basicg to see what made it tick, I found what appeared to be a data area that extended from X'8711' to X'8787'. Upon further investigation, I was able to pin down the areas where basicg stored the VIEW coordinates (the limits for the currently defined graphics screen). I also discovered another interesting storage area which I'll talk about at the end of this.

The addresses X'8735' and X'8736' store the first x coordinate (for the upper left corner). The addresses X'8737' and X'8738' stored the second x coordinate (for the lower right). The addresses X'8739' and X'873A' stored the frist Y coordinate (in TWO bytes!!), and like-wise the second was stored in X'873B' and X'873C'. What I did was poke the proper values for a 1024x256 graphics screen in. But that wasn't enough.

At addresses X'8784' and X'8785', I found the acceptable "column" numbers for the x coordinates (the port values, not the pixel values). I changed these to their proper X'00' and X'7F', respectively. At addresses X'8786' and X'8787', I found the "remainder" mask for the port values. These specified which bit in the byte was the "last acceptable" before it should ignore plotting that point. I set these to their proper X'00' and X'80'. That was all that was necessary. Now all graphics commands (except VIEW) will operate on the WHOLE of the graphics memory. you may GET and PUT off the screen (but withing the 1024x256 limits), LINE, CIRCLE, PAINT, etc!! You could then use the ports 140 and 141 to scroll over and see the extra areas of the screen memory!

As an added bonus, the CLR command cleared the ENTIRE graphics memory as well. But the CLR was slower because of all that extra memory it was clearing (I had though it was slow to BEGIN with). Now for that extra storage area I told you about. I was the image of port 131 at X'871E'. Armed with the knowledge, I could reset the bit 1 (which controls video waits), and thus speed up all graphics substantially. To use the high-speed CLR, POKE &H871E,253. To go back to the normal mode (no snow), POKE &H871E,255. For really impressive results, when you want to clr the screen, execute the following:

POKE &H871E,254:CLR:POKE &H871E,255

This appears to erase the screen instantly with no snow, by turning off the graphics screen while it erases! Now that Basicg can instantly erase the screen (and speed up painting and circles when you are drawing when the screen is not displayed), and all graphics commands can operate over the whole range of the graphics memory, just think of the possibilities!!

Ports (Model I)

EBH:  Serial Port
     IN                            OUT
     (Input Data)                  (Output Data)
B7:  Data-7                        Data-7
B6:  Data-6                        Data-6
B5:  Data-5                        Data-5
B4:  Data-4                        Data-4
B3:  Data-3                        Data-3
B2:  Data-2                        Data-2
B1:  Data-1                        Data-1
B0:  Data-0                        Data-0

EAH:  Serial Port
     IN                            OUT
     (Uart Status bits)            (Uart parameters set)
B7:  1=Data Available              1=Even Parity
B6:  0=Data sent (TBMT)            WD Lngth 00=5 01=7
B5:  1=Overrun Error               WD Lngth 10=6 11=8
B4:  1=Framing Error               0=1-Stop bit
B3:  1=Parity Error                1=No Parity
B2:  unused                        1=Transmit Enable
B1:  unused                        0=DTR on
B0:  unused                        0=RTS on

E9H:  Serial Port
     IN                            OUT
     (DIP Switches??)              (Set speeds)
B7:  Parity 0=Odd                   Set Baud rate (all bits)
B6:  Wd Length 00=5 01=7            110 = 22H   150 = 44H
B5:            10=6 11=8            300 = 55H   600 = 66H
B4:  Stop bits 0=1 1=2             1200 = 77H  2400 = AAH
B3:  Parity 0=enable               4800 = 66H  9600 = EEH
B2:  unused                        Bits 0-3 = Receive Speed
B1:  unused                        Bits 4-7 = Transmit Speed
B0:  unused

E8H:  Serial Port
     IN                            OUT
     (Signals Input)               (Reset Uart)
B7:  CTS                           Any value will reset the
B6:  DSR                           Uart
B5:  0=Carrier Detected
B4:  1?=Ring Indicate
B3:  unused
B2:  unused
B1:  unused
B0:  Serial data input

Ports (Model III)

FF: Cassette unit.       I/O
F8: Printer.             I/O

F4H: Disk Drive register port.
     IN                            OUT
B7:
B6:
B5:
B4:
B3:
B2:
B1:
B0:

F3: Disk Controller DATA register.
     Same specs as for WD1791 DDEN Disk Controller.
F2: Disk SECTOR register.
     For WD1791.
F1: Disk TRACK  register.
     For WD1791.
F0: Disk COMMAND/STATUS register.
     For WD1791.

C8-CF: Hard disk controller port addresses.
   Ports C8 to CF correspond to Winchester Disk controller
chip WD1010 registers 0 through 7. Port C8 in particular
is the port used to read/write data.
   See Western Digital manual for specs.

C1: ??
C0: ??

EC: ?                    I/O

EBH:  RS-232 data in/out port
     IN                            OUT
     (Data read from line)         (Data sent to line)
B7:  Data-7                        Data-7
B6:  Data-6                        Data-6
B5:  Data-5                        Data-5
B4:  Data-4                        Data-4
B3:  Data-3                        Data-3
B2:  Data-2                        Data-2
B1:  Data-1                        Data-1
B0:  Data-0                        Data-0

EAH: RS-232 status/control
     IN                            OUT
     (Uart Status & signals)       (Set UART parameters)
B7:  1=Data Available (input)      1=Even Parity, 0=Odd
B6:  1=Data Sent (output)          : Word length 00=5 01=7
B5:  1=Overrun Error               : Word length 10=6 11=8
B4:  1=Framing Error               0=1-Stop bit, 1=2.
B3:  1=Parity Error                0=Enable parity, 1=Disable
B2:  unused                        1?=Send BREAK signal
B1:  unused                        1=DTR off
B0:  unused                        1=RTS off

E9: RS-232 software switches and speed select
     IN                            OUT
     (DIP Switches)                (Baud rate select)
B7:  Parity 0=odd 1=even           ) Xmit baud rate B4-B7
B6:  Word length 00=5 01=7         )
B5:  Word length 10=6 11=8         )
B4:  Stop bits 0=1 1=2             )
B3:  Parity 0=enable 1=disable     ) Recv baud rate B0-B3
B2:  Baud rate select #2           )
B1:  Baud rate select #1           )
B0:  Baud rate select #0           )

E8: RS-232 Signals and reset
     IN                            OUT
     (Input signals)               (Reset)
B7:  CTS                           Any value will reset the
B6:  DSR                           interface.
B5:  Carrier Detect
B4:  Ring Indicate
B3:  unused
B2:  unused
B1:  Copy of serial input pin UART
B0:    (May be bit 0 instead)

E4: ?                    I/O
E0: ?                    I/O
9C: ? (4p only?)         O

Programming the Model 4 Function Keys - Colin Dunn

The Model 4 function keys are programmable...


In Model 3 mode:

	F1 = 16875 F2 = 16876 F3 = 16883

	POKE the above addresses with values for the F1, F2, and F3 keys...

If you use TRSDOS 6.2: F1=0918H F2=091AH F3=091CH SHIFT F1=0919H SHIFT F2=091BH SHIFT F3=091DH

	Poke these from BASIC or change the values from DEBUG. You can save the configuration with the SYSGEN command.

Changing the Model 4 Speed - Colin Dunn

It is possible to use configurations of 4MHZ III mode or 2MHZ IV mode...

To use a FAST 3 mode, execute POKE 16912,104. If you plan to do disk access, return to 2MHZ or tell your DOS that the computer is at 4MHZ. (For LDOS, use the command: SYSTEM (FAST) at LDOS READY)

To use the SLOW 4 mode, use a SYSTEM (SLOW) at TRSDOS READY. Going back to FAST mode in 4 mode is just a SYSTEM (FAST) away. TRSDOS 6 automatically takes care of disk access delays.

You may wonder, WHY DOES DISK ACCESS NEED SLOWER SPEED???? Answer: If you access a disk and the computer is running too fast, the disk drives get bad commands. A disk can be wiped out by accessing disks too quickly!!!

Controlling the Model 4 Sound Card - Colin Dunn

The Model 4 SOUND BOARD command are generally disappointing. When you use the JCL, you only get 7 tones and 31 L-O-N-G durations. Not good for games. BASIC does the same things. Why didn't RS include the PLAY command or a good SOUND command? By the way, the limited Sound command is accessed by SOUND T,D where: T=0 to 7 and D=0 to 31. Using a duration of 31 takes about 4-5 seconds to produce a tone. Worse yet, the tones don't allow a musical scale.

The SOUND BOARD is accessed through port 144 (90 HEX). It is used the same way the tape port on the III is used for sound. (Note: 4P users don't have to bother with port 144. Port 255 will do sound board access on the 4P since it lacks a cassette port. Here are some ideas on the use of the sound board:

Change the OUTS to port 144 in your favorite game programs. Find D3 FF sequences in the hex dump of your /CMD file. Change it to D3 90. Once you apply the patches, the sound goes to the Model 4 sound board.

Model 4 BASIC Commands - Colin Dunn

Have you ever felt lost in Model 4 BASIC?? Have you been wasting memory on MOD 3 routines which are built in commands in 4 mode? If so, read on!

A.	The INTEGER DIVISION COMMAND

	In 3 mode, you would do: A=INT(B/C) to get a remainder-free division. In 4 mode, just do this: A=B\C. Save a couple bytes and a some typing.

B.	INPUT$

	Have you ever had this show up in your programs? 10 A$=INKEY$:IF A$="" THEN 10

	If so, save some memory! Use A$=INPUT$(1)!!!

	Also, if you want password entry in a program, you simply use a$=INPUT$(X) where X is the number of characters to enter. All character codes are taken. There is no backspacing, and it won't display anything on the screen.

Model 4 Video Locations - Colin Dunn

In order to be able to POKE/PEEK the video display in Model 4 mode, you must first:

(a)

If using BASIC: set HIMEM to F3FFH, and POKE location 120 with 134, and also do an OUT 132,134.

(b)

If you're using machine language: Disable the interrupts (DI), and then perform an OUT to port 132 with 134.

The above will make the keyboard and screen memory accessible. To reverse this condition, use:

(a)

In BASIC: POKE 120,135:OUT 132,135. This will make normal RAM accessible and cancel out the use of keyboard and video memory.

(B)

In machine language: Out to port 132 with a 135. Also, re-enable the interrupts to keep the type-ahead and real-time clock and any other interrupt task active.

If you program the keyboard and screen access in machine language, place no programs higher than location F3FFH. If you do, the video RAM will load over the program, and any attempts to jump, call, or use data in addresses above F3FFH will fail. JUMPs and CALLs will crash the system!!!

The video memory extends from F800H to FF7FH (leaving 128 bytes at the top of memory untouched, but this limited storage has no practical use except for some machine language program variables and data areas).

Here's the info on what addresses are for what line:

(the line numbers are in decimal, but the addresses are in hex)

Line Number	Start Address	End Address
--------------------------------------
00	F800H	F84FH
01	F850H	F89FH
02	F8A0H	F8EFH
03	F8F0H	F93FH
04	F940H	F98FH
05	F990H	F9DFH
06	F9E0H	FA2FH
07	FA30H	FA7FH
08	FA80H	FACFH
09	FAD0H	FB1FH
10	FB20H	FB6FH
11	FB70H	FBBFH
12	FBC0H	FC0FH
13	FC10H	FC5FH
14	FC60H	FCAFH
15	FCB0H	FCFFH
16	FD00H	FD4FH
17	FD50H	FD9FH
18	FDA0H	FDEFH
19	FDF0H	FE3FH
20	FE40H	FE8FH
21	FE90H	FEDFH
22	FEE0H	FF2FH
23	FF30H	FF7FH

The Model 4 uses the same character set as the Model 3 as long as the reverse video is turned off. If you wish to use reverse video, first send CHR$ code 16 to the display, then switch in the video memory. You can only access inverse video and POKE the data if you SET bit 7 of the data going to the display. Example: Send ASCII code to display with this assembler program:

LD A,41H
LD HL,F800H
LD (HL),A

The above puts the normal video "A" on the screen. If you want reverse video, use this:

LD A,41H ; A
SET 7,A
LD HL,F800H
LD (HL),A

You can also calculate the reverse video strings by adding 128 to each value to send to the screen.

***** N O T E *****

If you enable the reverse video, you *CANNOT* use the graphics characters. To disable the reverse video and enable the graphics, send a CHR$ code 17 to the screen.

Undocumented Z-80 Opcodes - Developed from the article by Daniel Lunsford in TAS, V1. N6. pp53-55

In these opcodes, HX and LX represent the high- and low-order bytes of the IX register. HY and LY are analogous for the IY register. The timing for these new IX and IY instructions is 4 T-states longer than the equivalent H and L instructions..

Also, SLS means Shift Left and Set. This shifts the register left just as an SLA would, and then the LSB is set. The MSB goes into the Carry flag, and sign and parity are adjusted as expected.

New Opcode      Hex             Assembler Realization

SLS   A         CB 37           DEFW    37CBH
SLS   B         CB 30           DEFW    30CBH
SLS   C         CB 31           DEFW    31CBH
SLS   D         CB 32           DEFW    32CBH
SLS   E         CB 33           DEFW    33CBH
SLS   H         CB 34           DEFW    34CBH
SLS   L         CB 35           DEFW    35CBH
SLS   (HL)      CB 36           DEFW    36CBH

SLS   (IX+d)    DD CB dd 36     RLC (IX+d)
                                ORG $-1
                                DEFB 36H

SLS   (IY+d)    FD CB dd 36     RLC (IY+d)
                                ORG $-1
                                DEFB 36H

ADC   A,HX      DD 8C           DEFW    8CDDH
ADC   A,LX      DD 8D           DEFW    8DDDH
ADC   A,HY      FD 8C           DEFW    8CFDH
ADC   A,LY      FD 8D           DEFW    8DFDH

ADD   A,HX      DD 84           DEFW    84DDH
ADD   A,LX      DD 85           DEFW    85DDH
ADD   A,HY      FD 84           DEFW    84FDH
ADD   A,LY      FD 85           DEFW    85FDH

AND   HX        DD A4           DEFW    0A4DDH
AND   LX        DD A5           DEFW    0A5DDH
AND   HY        FD A4           DEFW    0A4FDH
AND   LY        FD A5           DEFW    0A5FDH

CP    HX        DD BC           DEFW    0BCDDH
CP    LX        DD BD           DEFW    0BDDDH
CP    HY        FD BC           DEFW    0BCFDH
CP    LY        FD BD           DEFW    0BDFDH

DEC   HX        DD 25           DEFW    25DDH
DEC   LX        DD 2D           DEFW    2DDDH
DEC   HY        FD 25           DEFW    25FDH
DEC   LY        FD 2D           DEFW    2DFDH

INC   HX        DD 24           DEFW    24DDH
INC   LX        DD 2C           DEFW    2CDDH
INC   HY        FD 24           DEFW    24FDH
INC   LY        FD 2C           DEFW    2CFDH

OR    HX        DD B4           DEFW    0B4DDH
OR    LX        DD B5           DEFW    0B5DDH
OR    HY        FD B4           DEFW    0B4FDH
OR    LY        FD B5           DEFW    0B5FDH

SBC   A,HX      DD 9C           DEFW    9CDDH
SBC   A,LX      DD 9D           DEFW    9DDDH
SBC   A,HY      FD 9C           DEFW    9CFDH
SBC   A,LY      FD 9D           DEFW    9DFDH

SUB   HX        DD 94           DEFW    94DDH
SUB   LX        DD 95           DEFW    95DDH
SUB   HY        FD 94           DEFW    94FDH
SUB   LY        FD 95           DEFW    95FDH

XOR   HX        DD AC           DEFW    0ACDDH
XOR   LX        DD AD           DEFW    0ADDDH
XOR   HY        FD AC           DEFW    0ACFDH
XOR   LY        FD AD           DEFW    0ADFDH

LD   HX,A       DD 67           DEFW    67DDH
LD   LX,A       DD 6F           DEFW    6FDDH
LD   HY,A       FD 67           DEFW    67FDH
LD   LY,A       FD 6F           DEFW    6FFDH

LD   HX,B       DD 60           DEFW    60DDH
LD   LX,B       DD 68           DEFW    68DDH
LD   HY,B       FD 60           DEFW    60FDH
LD   LY,B       FD 68           DEFW    68FDH

LD   HX,C       DD 61           DEFW    61DDH
LD   LX,C       DD 69           DEFW    69DDH
LD   HY,C       FD 61           DEFW    61FDH
LD   LY,C       FD 69           DEFW    69FDH

LD   HX,D       DD 62           DEFW    62DDH
LD   LX,D       DD 6A           DEFW    6ADDH
LD   HY,D       FD 62           DEFW    62FDH
LD   LY,D       FD 6A           DEFW    6AFDH

LD   HX,E       DD 63           DEFW    63DDH
LD   LX,E       DD 6B           DEFW    6BDDH
LD   HY,E       FD 63           DEFW    63FDH
LD   LY,E       FD 6B           DEFW    6BFDH

LD   HX,n       DD 26 n         DEFB    0DDH,26H,n
                             or DEFB    221,38,n

LD   LX,n       DD 2E n         DEFB    0DDH,2EH,n
                             or DEFB    221,46,n

LD   HY,n       FD 26 n         DEFB    0FDH,26H,n
                             or DEFB    253,38,n

LD   LY,n       FD 2E n         DEFB    0FDH,2EH,n
                             or DEFB    253,46,n

LD   HX,LX      DD 65           DEFW    65DDH
LD   LX,HX      DD 6C           DEFW    6CDDH
LD   HY,LY      FD 65           DEFW    65FDH
LD   LY,HY      FD 6C           DEFW    6CFDH

LD   A,HX       DD 7C           DEFW    7CDDH
LD   A,LX       DD 7D           DEFW    7DDDH
LD   A,HY       FD 7C           DEFW    7CFDH
LD   A,LY       FD 7D           DEFW    7DFDH

LD   B,HX       DD 44           DEFW    44DDH
LD   B,LX       DD 45           DEFW    45DDH
LD   B,HY       FD 44           DEFW    44FDH
LD   B,LY       FD 45           DEFW    45FDH

LD   C,HX       DD 4C           DEFW    4CDDH
LD   C,LX       DD 4D           DEFW    4DDDH
LD   C,HY       FD 4C           DEFW    4CFDH
LD   C,LY       FD 4D           DEFW    4DFDH

LD   D,HX       DD 54           DEFW    54DDH
LD   D,LX       DD 55           DEFW    55DDH
LD   D,HY       FD 54           DEFW    54FDH
LD   D,LY       FD 55           DEFW    55FDH

LD   E,HX       DD 5C           DEFW    5CDDH
LD   E,LX       DD 5D           DEFW    5DDDH
LD   E,HY       FD 5C           DEFW    5CFDH
LD   E,LY       FD 5D           DEFW    5DFDH

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