16 Oct
2015
16 Oct
'15
11:16 a.m.
Hey guys,
Posting this to various forums in the hopes of finding someone in the know -
I have this ASCI u68 system (6800 cpu) that I understand was used in
educational environments. I kind of have it running but know little about
assembly language programming, etc. Or the unit itself. Have any of you
ever messed with these? It looks like it has a serial connector on its
mainboard.. was trying to figure out a way if I could patch it to one of my
terminals.
Also trying to find some simple 6800 assembly programs/routines to test it
and see if it really works properly. There is an MC6821S chip on it (there
are three of them actually) and one in the middle is marked 'BAD'. I
understand those handle peripherals.
I'd also heard rumours there was a second board available for these that
gave them BASIC. I've never seen such a board for sale anywhere - wondered
if anyone had seen one in the wild.
Brad
16 Oct
16 Oct
1:06 p.m.
The Heathkit ET-3400 (another SBC trainer) also used the M6800 CPU. Now I
realize that the two machines probably have fairly different ROMs, but
otherwise some of the 3400 materials / programs should cross-over to the
u68. It might even simply be a matter of translating ROM calls..
Anyway, I have a full set of docs for the ET-3400. If you're interested, I
can find a way to get a copy to you.
-Bill
On Fri, Oct 16, 2015 at 11:16 AM, Brad <unclefalter at yahoo.ca> wrote:
Hey guys,
Posting this to various forums in the hopes of finding someone in the know
-
I have this ASCI u68 system (6800 cpu) that I understand was used in
educational environments. I kind of have it running but know little about
assembly language programming, etc. Or the unit itself. Have any of you
ever messed with these? It looks like it has a serial connector on its
mainboard.. was trying to figure out a way if I could patch it to one of my
terminals.
Also trying to find some simple 6800 assembly programs/routines to test it
and see if it really works properly. There is an MC6821S chip on it (there
are three of them actually) and one in the middle is marked 'BAD'. I
understand those handle peripherals.
I'd also heard rumours there was a second board available for these that
gave them BASIC. I've never seen such a board for sale anywhere - wondered
if anyone had seen one in the wild.
Brad
1:27 p.m.
Many thanks. I'll take a quick look online just to see if I can save you the trouble.
I'm surprised at how little documentation there is for this thing.
As a general rule, does anyone know -- if you have a single board computer like this with
serial connector, is that 'live' all the time? Or do you usually have to invoke a
program in order for a terminal to connect to it and use it?
-----Original Message-----
From: cctalk [mailto:cctalk-bounces at classiccmp.org] On Behalf Of drlegendre .
Sent: Friday, October 16, 2015 11:06 AM
To: General Discussion: On-Topic and Off-Topic Posts <cctalk at classiccmp.org>
Subject: Re: ASCI u68 (SystemX)
The Heathkit ET-3400 (another SBC trainer) also used the M6800 CPU. Now I realize that the
two machines probably have fairly different ROMs, but otherwise some of the 3400 materials
/ programs should cross-over to the u68. It might even simply be a matter of translating
ROM calls..
Anyway, I have a full set of docs for the ET-3400. If you're interested, I can find a
way to get a copy to you.
-Bill
On Fri, Oct 16, 2015 at 11:16 AM, Brad <unclefalter at yahoo.ca> wrote:
Hey guys,
Posting this to various forums in the hopes of finding someone in the
know
-
I have this ASCI u68 system (6800 cpu) that I understand was used in
educational environments. I kind of have it running but know little
about assembly language programming, etc. Or the unit itself. Have
any of you ever messed with these? It looks like it has a serial
connector on its mainboard.. was trying to figure out a way if I could
patch it to one of my terminals.
Also trying to find some simple 6800 assembly programs/routines to
test it and see if it really works properly. There is an MC6821S chip
on it (there are three of them actually) and one in the middle is
marked 'BAD'. I understand those handle peripherals.
I'd also heard rumours there was a second board available for these
that gave them BASIC. I've never seen such a board for sale anywhere
- wondered if anyone had seen one in the wild.
Brad
-----
No virus found in this message.
Checked by AVG - www.avg.com
Version: 2015.0.6172 / Virus Database: 4447/10805 - Release Date: 10/12/15
1:34 p.m.
There has to be some support for it in the ROM ... otherwise it won't do
anything ... and may in fact cause the system to behave strangely (having
an uninitialized ACIA just sitting there on the bus) ... I'm fairly new at
writing assembly code but I found it was a few hundred lines of code to
implement a simple little monitor that could read strings from a serial
line and echo them back (on 6502, for comparison's sake). I guess since
this is a pre-built board, not something you made from scratch, this may
have already been done for you :O If the board looks OK ... no shorts, etc
... might as well power it up with a tty and see what happens! Assuming
there is an ACIA on board and it's wired to that port ...
Best,
Sean
On Fri, Oct 16, 2015 at 2:27 PM, Brad <unclefalter at yahoo.ca> wrote:
Many thanks. I'll take a quick look online just
to see if I can save you
the trouble. I'm surprised at how little documentation there is for this
thing.
As a general rule, does anyone know -- if you have a single board computer
like this with serial connector, is that 'live' all the time? Or do you
usually have to invoke a program in order for a terminal to connect to it
and use it?
-----Original Message-----
From: cctalk [mailto:cctalk-bounces at classiccmp.org] On Behalf Of
drlegendre .
Sent: Friday, October 16, 2015 11:06 AM
To: General Discussion: On-Topic and Off-Topic Posts <
cctalk at classiccmp.org>
Subject: Re: ASCI u68 (SystemX)
The Heathkit ET-3400 (another SBC trainer) also used the M6800 CPU. Now I
realize that the two machines probably have fairly different ROMs, but
otherwise some of the 3400 materials / programs should cross-over to the
u68. It might even simply be a matter of translating ROM calls..
Anyway, I have a full set of docs for the ET-3400. If you're interested, I
can find a way to get a copy to you.
-Bill
On Fri, Oct 16, 2015 at 11:16 AM, Brad <unclefalter at yahoo.ca> wrote:
Hey guys,
Posting this to various forums in the hopes of finding someone in the
know
-
I have this ASCI u68 system (6800 cpu) that I understand was used in
educational environments. I kind of have it running but know little
about assembly language programming, etc. Or the unit itself. Have
any of you ever messed with these? It looks like it has a serial
connector on its mainboard.. was trying to figure out a way if I could
patch it to one of my terminals.
Also trying to find some simple 6800 assembly programs/routines to
test it and see if it really works properly. There is an MC6821S chip
on it (there are three of them actually) and one in the middle is
marked 'BAD'. I understand those handle peripherals.
I'd also heard rumours there was a second board available for these
that gave them BASIC. I've never seen such a board for sale anywhere
- wondered if anyone had seen one in the wild.
Brad
-----
No virus found in this message.
Checked by AVG - www.avg.com
Version: 2015.0.6172 / Virus Database: 4447/10805 - Release Date: 10/12/15
1:55 p.m.
-----Oorspronkelijk bericht-----
From: Brad
Sent: Friday, October 16, 2015 8:27 PM
To: 'General Discussion: On-Topic and Off-Topic Posts'
Subject: RE: ASCI u68 (SystemX)
Many thanks. I'll take a quick look online just to see if I can save you
the trouble. I'm surprised at how little documentation there is for this
thing.
As a general rule, does anyone know -- if you have a single board computer
like this with serial connector, is that 'live' all the time? Or do you
usually have to invoke a program in order for a terminal to connect to it
and use it?
---------
From all the SBCs that I know, the standard serial port
is always active. The on-board monitor with very basic
commands uses it as only means of communication.
After reset the monitor will "print" possible a one-line
identification and on the next line some form of prompt.
Could be * or . or > or - or whatever.
You need to know the com ports settings, but it prints
an ID line you can try several baudrates. 9600 is a good
start.
If you want 6800 info, ask. I can dream 6800 opcodes!
INX=$08, LDA # =$86, DEX=$09, STAindexed =$A6. etc.
Depending on the RAM size, I have a StarTrek version
in 6800 assembler that uses a serial port ... IIRC, it
is some 1.5k
- Henk
3:37 p.m.
Thanks Henk,
I tried that. No prompt comes up with PUTTY on serial set at any baud rate. Instead on
the LED display I get a C, or an S sometimes.
-----Original Message-----
From: cctalk [mailto:cctalk-bounces at classiccmp.org] On Behalf Of Henk Gooijen
Sent: Friday, October 16, 2015 11:56 AM
To: General Discussion: On-Topic and Off-Topic Posts <cctalk at classiccmp.org>
Subject: Re: ASCI u68 (SystemX)
-----Oorspronkelijk bericht-----
From: Brad
Sent: Friday, October 16, 2015 8:27 PM
To: 'General Discussion: On-Topic and Off-Topic Posts'
Subject: RE: ASCI u68 (SystemX)
Many thanks. I'll take a quick look online just to see if I can save you the trouble.
I'm surprised at how little documentation there is for this thing.
As a general rule, does anyone know -- if you have a single board computer like this with
serial connector, is that 'live' all the time? Or do you usually have to invoke a
program in order for a terminal to connect to it and use it?
---------
From all the SBCs that I know, the standard serial port
is always active. The on-board monitor with very basic commands uses it as only means of
communication.
After reset the monitor will "print" possible a one-line
identification and on the next line some form of prompt.
Could be * or . or > or - or whatever.
You need to know the com ports settings, but it prints an ID line you can try several
baudrates. 9600 is a good start.
If you want 6800 info, ask. I can dream 6800 opcodes!
INX=$08, LDA # =$86, DEX=$09, STAindexed =$A6. etc.
Depending on the RAM size, I have a StarTrek version in 6800 assembler that uses a serial
port ... IIRC, it is some 1.5k
- Henk
-----
No virus found in this message.
Checked by AVG - www.avg.com
Version: 2015.0.6172 / Virus Database: 4447/10805 - Release Date: 10/12/15
3:55 p.m.
Often you have to press RETURN or SPACE a few
times to wake up the serial connection and set the
baud rate; if you put a scope on the RX and TX
lines, do you see the incoming signal from the
terminal and does anything get sent back?
Can you trace the RX and TX signals to see what
chips are used to convert RS-232 to TTL?
m
----- Original Message -----
From: "Brad" <unclefalter at yahoo.ca>
To: "'General Discussion: On-Topic and Off-Topic
Posts'" <cctalk at classiccmp.org>
Sent: Friday, October 16, 2015 4:37 PM
Subject: RE: ASCI u68 (SystemX)
Thanks Henk,
I tried that. No prompt comes up with PUTTY on
serial set at any baud rate. Instead on the LED
display I get a C, or an S sometimes.
-----Original Message-----
From: cctalk
[mailto:cctalk-bounces at classiccmp.org] On Behalf
Of Henk Gooijen
Sent: Friday, October 16, 2015 11:56 AM
To: General Discussion: On-Topic and Off-Topic
Posts <cctalk at classiccmp.org>
Subject: Re: ASCI u68 (SystemX)
-----Oorspronkelijk bericht-----
From: Brad
Sent: Friday, October 16, 2015 8:27 PM
To: 'General Discussion: On-Topic and Off-Topic
Posts'
Subject: RE: ASCI u68 (SystemX)
Many thanks. I'll take a quick look online just
to see if I can save you the trouble. I'm
surprised at how little documentation there is for
this thing.
As a general rule, does anyone know -- if you have
a single board computer like this with serial
connector, is that 'live' all the time? Or do you
usually have to invoke a program in order for a
terminal to connect to it and use it?
---------
From all the SBCs that I know, the standard serial
port is always active. The on-board monitor with
very basic commands uses it as only means of
communication.
After reset the monitor will "print" possible a
one-line identification and on the next line some
form of prompt.
Could be * or . or > or - or whatever.
You need to know the com ports settings, but it
prints an ID line you can try several baudrates.
9600 is a good start.
If you want 6800 info, ask. I can dream 6800
opcodes!
INX=$08, LDA # =$86, DEX=$09, STAindexed =$A6.
etc.
Depending on the RAM size, I have a StarTrek
version in 6800 assembler that uses a serial port
... IIRC, it is some 1.5k
- Henk
-----
No virus found in this message.
Checked by AVG - www.avg.com
Version: 2015.0.6172 / Virus Database:
4447/10805 - Release Date: 10/12/15
7:16 p.m.
On Fri, 16 Oct 2015, Brad wrote:
Thanks Henk,
I tried that. No prompt comes up with PUTTY on serial set at any baud
rate. Instead on the LED display I get a C, or an S sometimes.
Check for activity on lines 2 and 3, if it is a DB25.
You have not yet confirmed that you have it cabled correctly (DTE?, DCE?
null-modem?)
17 Oct
17 Oct
3:10 a.m.
OK. Did you post a link to some pictures? That can be helpful,
I missed the link if you did post it. The picture can help in
understanding what you have. I already know it has the 6800 :-)
and three 6821 PIAs. Is there also a 6850 ACIA on board?
Do you have some documentation? It could well be possible that
all you have after power up is the keypad and 7-segment displays
as on the MEK6800D2.
Check the power supply on the M6800 CPU. If you have a scope
you can check for activiy on the address and data pins, and the
"phi2" pin and VMA pin. I f we get further I probably need to get
the M6800 user manual on my desk.
- Henk
-----Oorspronkelijk bericht-----
From: Brad
Sent: Friday, October 16, 2015 10:37 PM
To: 'General Discussion: On-Topic and Off-Topic Posts'
Subject: RE: ASCI u68 (SystemX)
Thanks Henk,
I tried that. No prompt comes up with PUTTY on serial set at any baud rate.
Instead on the LED display I get a C, or an S sometimes.
-----Original Message-----
From: cctalk [mailto:cctalk-bounces at classiccmp.org] On Behalf Of Henk
Gooijen
Sent: Friday, October 16, 2015 11:56 AM
To: General Discussion: On-Topic and Off-Topic Posts <cctalk at classiccmp.org>
Subject: Re: ASCI u68 (SystemX)
-----Oorspronkelijk bericht-----
From: Brad
Sent: Friday, October 16, 2015 8:27 PM
To: 'General Discussion: On-Topic and Off-Topic Posts'
Subject: RE: ASCI u68 (SystemX)
Many thanks. I'll take a quick look online just to see if I can save you
the trouble. I'm surprised at how little documentation there is for this
thing.
As a general rule, does anyone know -- if you have a single board computer
like this with serial connector, is that 'live' all the time? Or do you
usually have to invoke a program in order for a terminal to connect to it
and use it?
---------
From all the SBCs that I know, the standard serial port
is always active.
The on-board monitor with very basic commands uses it as only
means of
communication.
After reset the monitor will "print" possible a one-line identification and
on the next line some form of prompt.
Could be * or . or > or - or whatever.
You need to know the com ports settings, but it prints an ID line you can
try several baudrates. 9600 is a good start.
If you want 6800 info, ask. I can dream 6800 opcodes!
INX=$08, LDA # =$86, DEX=$09, STAindexed =$A6. etc.
Depending on the RAM size, I have a StarTrek version in 6800 assembler that
uses a serial port ... IIRC, it is some 1.5k
- Henk
-----
No virus found in this message.
Checked by AVG - www.avg.com
Version: 2015.0.6172 / Virus Database: 4447/10805 - Release Date: 10/12/15
16 Oct
16 Oct
1:17 p.m.
Hi Brad,
I have a MEK6800 so not quite the same board but I know a little bit about
6800s ... I would suggest referring back to the original publications from
Mot ... there is a M6800 Applications Manual and a M6800 Programming Manual
... those are canonical and you should be able to find both on Bitsavers
... a nice "third party" book is "The 6800 Microprocessor" by Jack
Quinn on
Merrill press ... you should be able to find a copy cheap ... few bucks.
Once you get into it a little bit, I think you'll find they're pretty
friendly to interface and program ... I/O is all memory-mapped ... and you
will appreciate having that extra accumulator and the 16-bit index register
handy if you're used to playing with the 6502 ... :O
Best,
Sean
On Fri, Oct 16, 2015 at 12:16 PM, Brad <unclefalter at yahoo.ca> wrote:
Hey guys,
Posting this to various forums in the hopes of finding someone in the know
-
I have this ASCI u68 system (6800 cpu) that I understand was used in
educational environments. I kind of have it running but know little about
assembly language programming, etc. Or the unit itself. Have any of you
ever messed with these? It looks like it has a serial connector on its
mainboard.. was trying to figure out a way if I could patch it to one of my
terminals.
Also trying to find some simple 6800 assembly programs/routines to test it
and see if it really works properly. There is an MC6821S chip on it (there
are three of them actually) and one in the middle is marked 'BAD'. I
understand those handle peripherals.
I'd also heard rumours there was a second board available for these that
gave them BASIC. I've never seen such a board for sale anywhere - wondered
if anyone had seen one in the wild.
Brad
8:12 p.m.
On 2015-Oct-16, at 9:16 AM, Brad wrote:
Hey guys,
Posting this to various forums in the hopes of finding someone in the know -
I have this ASCI u68 system (6800 cpu) that I understand was used in
educational environments. I kind of have it running but know little about
assembly language programming, etc. Or the unit itself. Have any of you
ever messed with these? It looks like it has a serial connector on its
mainboard.. was trying to figure out a way if I could patch it to one of my
terminals.
Also trying to find some simple 6800 assembly programs/routines to test it
and see if it really works properly. There is an MC6821S chip on it (there
are three of them actually) and one in the middle is marked 'BAD'. I
understand those handle peripherals.
I'd also heard rumours there was a second board available for these that
gave them BASIC. I've never seen such a board for sale anywhere - wondered
if anyone had seen one in the wild.
I'm not acquainted with this model, but found pic here:
http://www.old-computers.com/museum/computer.asp?st=1&c=758
Too bad the pic is so small, can't make out much.
Looks like a pretty buffed out microproc trainer system, but such things were getting a
little passe by 1979, at least if that was a new design for the 6800.
Motorola was producing a similar thing in the form of the MEK6800 3 or more years earlier
(Motorola Evalution Kit 6800, with hex keypad and LED display).
Having the keypad and LED hex display there, it's native mode is likely to be running
a monitor operated through that keypad & display.
What one would expect is to be able to enter machine language into memory via the keypad
and then jump to it to execute.
All sorts of things are possible. It could be using their own monitor, it could be using a
modified version of JBUG (moto's monitor for the MEK6800), or MikBUG, it could have
moto's serial line monitor in ROM which might be a switch config option or you jump to
via the keypad and then control it from a console terminal, it might have routines for IO
to the serial line in ROM, and so on.
You can anticipate one of the 6821s will be for IO control of the keypad/hex display, one
of them is probably general purpose IO lines out to one of those connectors.
If there is no 6850 or other UART, the third 6821 may be for a bit-banged serial line, as
moto had routines for doing that going back to their early monitor and evaluation boards
(which I never understood - it was more trouble than just using their own 6850 UART).
A closeup pic could be a little more informative.
(I have some degree of experience with the 6800: written assorted assembly programs for
the 6800 going back to hand assembled programs for a moto evaluation board in 1978, have a
SWTPC 6800, and a MEK6800).
9:30 p.m.
Here's some detail shots of the unit (including two of the front and back of
the mainboard). Note the 6821 in the middle that has 'BAD' scratched into
it.
Front:
http://s1381.photobucket.com/user/unclefalter/media/20151016_191325_zpscaec0
dg8.jpg.html
http://s1381.photobucket.com/user/unclefalter/media/20151016_191426_zpsmagz2
dcc.jpg.html
Back:
http://s1381.photobucket.com/user/unclefalter/media/20151016_192343_zpsdgtag
rl1.jpg.html
Keypad:
http://s1381.photobucket.com/user/unclefalter/media/20151016_192440_zpsioiku
zdu.jpg.html
-----Original Message-----
From: cctalk [mailto:cctalk-bounces at classiccmp.org] On Behalf Of Brent
Hilpert
Sent: Friday, October 16, 2015 6:12 PM
To: General Discussion: On-Topic and Off-Topic Posts <cctalk at classiccmp.org>
Subject: Re: ASCI u68 (SystemX)
On 2015-Oct-16, at 9:16 AM, Brad wrote:
Hey guys,
Posting this to various forums in the hopes of finding someone in the
know - I have this ASCI u68 system (6800 cpu) that I understand was
used in educational environments. I kind of have it running but know
little about assembly language programming, etc. Or the unit itself.
Have any of you ever messed with these? It looks like it has a serial
connector on its mainboard.. was trying to figure out a way if I could
patch it to one of my terminals.
Also trying to find some simple 6800 assembly programs/routines to
test it and see if it really works properly. There is an MC6821S chip
on it (there are three of them actually) and one in the middle is
marked 'BAD'. I understand those handle peripherals.
I'd also heard rumours there was a second board available for these
that gave them BASIC. I've never seen such a board for sale anywhere
- wondered if anyone had seen one in the wild.
I'm not acquainted with this model, but found pic here:
http://www.old-computers.com/museum/computer.asp?st=1&c=758
Too bad the pic is so small, can't make out much.
Looks like a pretty buffed out microproc trainer system, but such things
were getting a little passe by 1979, at least if that was a new design for
the 6800.
Motorola was producing a similar thing in the form of the MEK6800 3 or more
years earlier (Motorola Evalution Kit 6800, with hex keypad and LED
display).
Having the keypad and LED hex display there, it's native mode is likely to
be running a monitor operated through that keypad & display.
What one would expect is to be able to enter machine language into memory
via the keypad and then jump to it to execute.
All sorts of things are possible. It could be using their own monitor, it
could be using a modified version of JBUG (moto's monitor for the MEK6800),
or MikBUG, it could have moto's serial line monitor in ROM which might be a
switch config option or you jump to via the keypad and then control it from
a console terminal, it might have routines for IO to the serial line in ROM,
and so on.
You can anticipate one of the 6821s will be for IO control of the keypad/hex
display, one of them is probably general purpose IO lines out to one of
those connectors.
If there is no 6850 or other UART, the third 6821 may be for a bit-banged
serial line, as moto had routines for doing that going back to their early
monitor and evaluation boards (which I never understood - it was more
trouble than just using their own 6850 UART).
A closeup pic could be a little more informative.
(I have some degree of experience with the 6800: written assorted assembly
programs for the 6800 going back to hand assembled programs for a moto
evaluation board in 1978, have a SWTPC 6800, and a MEK6800).
-----
No virus found in this message.
Checked by AVG - www.avg.com
Version: 2015.0.6172 / Virus Database: 4447/10805 - Release Date: 10/12/15
11:46 p.m.
On 2015-Oct-16, at 7:30 PM, Brad wrote:
Here's some detail shots of the unit (including
two of the front and back of
the mainboard). Note the 6821 in the middle that has 'BAD' scratched into
it.
Front:
http://s1381.photobucket.com/user/unclefalter/media/20151016_191325_zpscaec…
http://s1381.photobucket.com/user/unclefalter/media/20151016_191426_zpsmagz…
Back:
http://s1381.photobucket.com/user/unclefalter/media/20151016_192343_zpsdgta…
Keypad:
http://s1381.photobucket.com/user/unclefalter/media/20151016_192440_zpsioik…
From what can be readily discerned, with some
presumption, in functional not numeric order:
IC26 6875 clock generator
IC22 68B00 processor
. . obviously
IC7 TBP18S22 PROM 256*8
probably for address mapping of the RAM / ROM / IO.
IC19 2716 EPROM 2K*8 (or 2708 1K*8, note jumpers)
firmware/monitor ROM
IC18 2716 EPROM 2K*8 (or 2708 1K*8, note jumpers)
optional ROM
IC16 6514 SRAM 1024*4
IC17 6514 SRAM 1024*4
1 KBytes of RAM
IC30 6821 IO 2*8+4
IC31 6821 IO 2*8+4
IO to the keypad & LED display.
It looks like the hex-to-7-seg decoding is done in software,
over on the kbd/display PCB is a CA3082 7*NPN-tran, presumably
used as LED drivers. One of the chips is masked by the photoflash.
IC29 6821 IO 2*8+4
Goes to connector P1, just GPIO pins to play with.
IC15 6850 UART
IC13 1489 RS232 receiver
IC28 75150 line driver
IC25 4702 bit-rate generator
Comprise a serial line interface.
Not clear how the bit-rate is set, I'm guessing the rate selection pins of the
4702
are fed by IC14 74175 latch, fed in turn from IO pins on IC30, so the baud rate
would be
be under programmatic control.
IC27 555 timer
Not clear what that's for, might be an oscillator/timer for kbd/display
scanning,
feeding into IC30 or 31.
The remaining chips are bus drivers and a little glue logic.
--
It's pretty straightforward for what it is.
Date codes of 1981, but the support for 2708 and 2716 EPROMs suggest the design is a few
years earlier.
As IC30, the bad 6821, is involved in the keyboard/display you might try pulling it and
replacing it with IC29.
If you want to be particular, pull it and check for bad voltages and current limits on the
IO pins before plugging in a sub.
The expectation if it's running properly is that you'd press a key for a command
followed by hex address or data,
e.g. EXAMine, enter the address XXXX, displayed as entered, memory contents displayed on
entering 4th address digit.
11:59 p.m.
Thanks so much Brent! Your insight on the 6821 proved to make this thing
run way better! Swapping 29 and 30, the system 'boots up' consistently and
properly. Before, you'd hit reset and then any key and it might come up or
it might not, or it might generate weird messages and then go dark. Now it
comes up every time.
I connected the RS232 again and tried bauds between 110 and 9600 but no
dice. I'm assuming bits, parity etc are all standard.. hrmmm. Curious now.
Wish a manual still existed somewhere.
-----Original Message-----
From: cctalk [mailto:cctalk-bounces at classiccmp.org] On Behalf Of Brent
Hilpert
Sent: Friday, October 16, 2015 9:46 PM
To: General Discussion: On-Topic and Off-Topic Posts <cctalk at classiccmp.org>
Subject: Re: ASCI u68 (SystemX)
On 2015-Oct-16, at 7:30 PM, Brad wrote:
Here's some detail shots of the unit (including
two of the front and
back of the mainboard). Note the 6821 in the middle that has 'BAD'
scratched into it.
Front:
http://s1381.photobucket.com/user/unclefalter/media/20151016_191325_zp
scaec0dg8.jpg.html
http://s1381.photobucket.com/user/unclefalter/media/20151016_191426_zp
smagz2dcc.jpg.html
Back:
http://s1381.photobucket.com/user/unclefalter/media/20151016_192343_zp
sdgtagrl1.jpg.html
Keypad:
http://s1381.photobucket.com/user/unclefalter/media/20151016_192440_zp
sioikuzdu.jpg.html
From what can be readily discerned, with some
presumption, in functional not
numeric order:
IC26 6875 clock generator
IC22 68B00 processor
. . obviously
IC7 TBP18S22 PROM 256*8
probably for address mapping of the RAM / ROM / IO.
IC19 2716 EPROM 2K*8 (or 2708 1K*8, note jumpers)
firmware/monitor ROM
IC18 2716 EPROM 2K*8 (or 2708 1K*8, note jumpers)
optional ROM
IC16 6514 SRAM 1024*4
IC17 6514 SRAM 1024*4
1 KBytes of RAM
IC30 6821 IO 2*8+4
IC31 6821 IO 2*8+4
IO to the keypad & LED display.
It looks like the hex-to-7-seg decoding is done in software,
over on the kbd/display PCB is a CA3082 7*NPN-tran, presumably
used as LED drivers. One of the chips is masked by the photoflash.
IC29 6821 IO 2*8+4
Goes to connector P1, just GPIO pins to play with.
IC15 6850 UART
IC13 1489 RS232 receiver
IC28 75150 line driver
IC25 4702 bit-rate generator
Comprise a serial line interface.
Not clear how the bit-rate is set, I'm guessing the rate selection
pins of the 4702
are fed by IC14 74175 latch, fed in turn from IO pins on IC30, so
the baud rate would be
be under programmatic control.
IC27 555 timer
Not clear what that's for, might be an oscillator/timer for
kbd/display scanning,
feeding into IC30 or 31.
The remaining chips are bus drivers and a little glue logic.
--
It's pretty straightforward for what it is.
Date codes of 1981, but the support for 2708 and 2716 EPROMs suggest the
design is a few years earlier.
As IC30, the bad 6821, is involved in the keyboard/display you might try
pulling it and replacing it with IC29.
If you want to be particular, pull it and check for bad voltages and current
limits on the IO pins before plugging in a sub.
The expectation if it's running properly is that you'd press a key for a
command followed by hex address or data, e.g. EXAMine, enter the address
XXXX, displayed as entered, memory contents displayed on entering 4th
address digit.
-----
No virus found in this message.
Checked by AVG - www.avg.com
Version: 2015.0.6172 / Virus Database: 4447/10805 - Release Date: 10/12/15
17 Oct
17 Oct
12:33 a.m.
My guess is the RS232 is not involved in the initial-boot monitor, I wouldn't
necessarily be expecting anything from it at reset.
At this point I'd be aiming to figure out the keypad/display operation. The firmware
EPROM likely maps to the upper 2K of address space as the reset vector is at FFFE,FFFF.
EXAMining the contents of those two bytes (big-endian order) may produce an address in the
range F8xx-FFxx, the entry point to the monitor.
If that pans out and the memory contents in that range look suitably random or
differentiated then it would affirm the ROM is in that range.
Or poke around with EXAMine to try to locate the RAM, then figure out the command to load
RAM, and EXAMine it to see if you can get back what you entered.
There was a bunch of writing on a cover plate which could be seen but not discerned in a
photo, was that perhaps a command structure for the keypad?
If you can load RAM, you can enter and execute a program that modifies memory, but
you'll need to know the memory map in more detail to do IO.
Could figure out the address mapping for the IO by experimentation and inference from the
18S22, some reverse engineering around the 18S22 would help.
Or there's dumping and disassembling the monitor EPROM which might turn up IO
addresses, perhaps routines for character IO, maybe a console monitor or a serial-line
download routine, etc.
On 2015-Oct-16, at 9:59 PM, Brad wrote:
Thanks so much Brent! Your insight on the 6821 proved
to make this thing
run way better! Swapping 29 and 30, the system 'boots up' consistently and
properly. Before, you'd hit reset and then any key and it might come up or
it might not, or it might generate weird messages and then go dark. Now it
comes up every time.
I connected the RS232 again and tried bauds between 110 and 9600 but no
dice. I'm assuming bits, parity etc are all standard.. hrmmm. Curious now.
Wish a manual still existed somewhere.
-----Original Message-----
From: cctalk [mailto:cctalk-bounces at classiccmp.org] On Behalf Of Brent
Hilpert
Sent: Friday, October 16, 2015 9:46 PM
To: General Discussion: On-Topic and Off-Topic Posts <cctalk at classiccmp.org>
Subject: Re: ASCI u68 (SystemX)
On 2015-Oct-16, at 7:30 PM, Brad wrote:
Here's some detail shots of the unit
(including two of the front and
back of the mainboard). Note the 6821 in the middle that has 'BAD'
scratched into it.
Front:
http://s1381.photobucket.com/user/unclefalter/media/20151016_191325_zp
scaec0dg8.jpg.html
http://s1381.photobucket.com/user/unclefalter/media/20151016_191426_zp
smagz2dcc.jpg.html
Back:
http://s1381.photobucket.com/user/unclefalter/media/20151016_192343_zp
sdgtagrl1.jpg.html
Keypad:
http://s1381.photobucket.com/user/unclefalter/media/20151016_192440_zp
sioikuzdu.jpg.html
From what can be readily discerned, with some
presumption, in functional not
numeric order:
IC26 6875 clock generator
IC22 68B00 processor
. . obviously
IC7 TBP18S22 PROM 256*8
probably for address mapping of the RAM / ROM / IO.
IC19 2716 EPROM 2K*8 (or 2708 1K*8, note jumpers)
firmware/monitor ROM
IC18 2716 EPROM 2K*8 (or 2708 1K*8, note jumpers)
optional ROM
IC16 6514 SRAM 1024*4
IC17 6514 SRAM 1024*4
1 KBytes of RAM
IC30 6821 IO 2*8+4
IC31 6821 IO 2*8+4
IO to the keypad & LED display.
It looks like the hex-to-7-seg decoding is done in software,
over on the kbd/display PCB is a CA3082 7*NPN-tran, presumably
used as LED drivers. One of the chips is masked by the photoflash.
IC29 6821 IO 2*8+4
Goes to connector P1, just GPIO pins to play with.
IC15 6850 UART
IC13 1489 RS232 receiver
IC28 75150 line driver
IC25 4702 bit-rate generator
Comprise a serial line interface.
Not clear how the bit-rate is set, I'm guessing the rate selection
pins of the 4702
are fed by IC14 74175 latch, fed in turn from IO pins on IC30, so
the baud rate would be
be under programmatic control.
IC27 555 timer
Not clear what that's for, might be an oscillator/timer for
kbd/display scanning,
feeding into IC30 or 31.
The remaining chips are bus drivers and a little glue logic.
--
It's pretty straightforward for what it is.
Date codes of 1981, but the support for 2708 and 2716 EPROMs suggest the
design is a few years earlier.
As IC30, the bad 6821, is involved in the keyboard/display you might try
pulling it and replacing it with IC29.
If you want to be particular, pull it and check for bad voltages and current
limits on the IO pins before plugging in a sub.
The expectation if it's running properly is that you'd press a key for a
command followed by hex address or data, e.g. EXAMine, enter the address
XXXX, displayed as entered, memory contents displayed on entering 4th
address digit.
-----
No virus found in this message.
Checked by AVG - www.avg.com
Version: 2015.0.6172 / Virus Database: 4447/10805 - Release Date: 10/12/15
3711
days inactive
3712
days old
14 comments
7 participants
participants (7)
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