test-drb April 1999

test-drb@ccmp.vtda.org

170 participants
1190 discussions

by mtapley＠swri.edu

>From: Dwight Elvey <elvey(a)hal.com> ... > There were several Forth machines done over the years, ... >Harris made one that was used quite >often for space applications because it was fast >and could run with smaller amounts of code ( a feature >of Forth ). Still makes, the RTX2010. The IMAGE mission that I'm working on will have three of them aboard, running 3 of the 6 instruments, when it lifts off in early 2000. - Mark

27 years

WTB: TRIMM DA523-331

by jhfine＠idirect.com

I am not positive if this is the correct part number. Have you ever seen a PDP-11/34 top loading rack mounted box? About the same size! Also top loading. About 10 1/4" high and a 19" rack. BUT, this is for a Qbus back plane with at least 10 slots (there could be as many as 16). And I suspect that the first 3 slots may be ABCD like the BA23 box and the rest are AB/AB also like the BA23 box. Sincerely yours, Jerome Fine

27 years

Computer Storage

by allisonp＠world.std.com

<What precautions should I take in storing computers here? < <Do I need to insulate / heat the building? Within bounds no. Most componenets will take 0-50C as commercial temperture range. Sharp changes in temperature are not beneficial so if cold leave it that way, if warm don't shock cool it. If you can stay within 10-40C there should be no problem. Electrolytic capacitors however, dry out of kept too hot for too long. <Should I install a dehumidifier (I think I can get hold of one)? Moisture is the enemy during the seasons where you get the greatest cyclic temperature changes. And most winters. <Do I need (for example) to wrap each computer up in plastic with a packet o <silica gel? If it's a sealed bag aroung the equipment, that works very well. the bag has to be sealed or the silica will saturate quickly. the silica can be dried in a warm oven to drive out the moisture and render it effective again. Also the package (system, box, rack) should be made vermin proof as insects can leave deposits and rodents can chew, nest or soil things. Allison

27 years

Commodore vs Apple [WAS: Re: stepping machanism of Apple Disk

by allisonp＠world.std.com

<This must have varied significantly with geography. In Ontario, Canada, <where I grew up, Commodore was king, both at home and in schools. Most <schools' first computers were PETs, either alone or in clusters, followed I'd say so. I'd see one school district with TRS80 and the next one over apples or commies. Made teachers nuts. Allison

27 years

z80 timing... 6502 timing

by allisonp＠world.std.com

<the relatively short memory access strobe, while I was talking about the <frequency at which they occur, as defined in the spec. I agree completely Yes so? Often the z80 is moving 16bits, with 8bit wide memory it's going to take several cycles. If it were a z280 that would be even more biased as it uses fewer "ticks" per cycle and the bus is 16bits wide. Counting ticks or whatever as I've repeatedly stated meaningless save for discussions of how memory is used and not who is faster. An aside at this point, the z280 runs different cycle timing as @4mhz would be the base z80 of the same speed and the z380 (in z80 native mode) beats that as the cycles have been shortend again. <personal. The fact remains, that the memory CYCLE is three clock ticks <long, as defined in the spec (though I haven't looked at it in 15 years or It is not and Like I said the spec is infront of me as I type. Worst case its 2. But that in itself is again meaningless. <so since I haven't yet unearthed my Zilog or Mostek data books) and if you <look at the pictures you saw with your logic analyzer, you should have see <two read pulses of whatever lenght they were, spaced at very nearly 750 ns <each time you saw the execution of an absolute jump, or any other <instruction which consists of an opcode followed by a 16-bit address. The <same is true of writes. They take one memory cycle, which is three clock <ticks long, for each byte, although the memory write strobe is a mite <shorter than the read strobe, IIRC, which I might not, but . . . Your memory is faulty. and that 750ns bumber is still meaningless. they only number for comparative purposes is the amount of time it takes to do an absolute jump. For Z80 @4mhz that will be 2.5us. It will require memory in the 250ns range to do it. <were inserted as they often were for M1 cycles. Nevertheless, commonly use <instructions were MUCH faster on the 2 MHz 6502, than on the 4 MHz Z-80. A 2mhz 6502 executes a 1byte (say INX) instuction in 2 machine cycles and that takes 1uS. A 4mhz INC B (any register) takes 4 z80 clocks at 4mhz... damm if that doesn't happen to be 1uS! Where is the speed difference? According to my book a 6502 absolute jump takes 3-5 cycles and in the 5 cycle case its 2.5 us. <probably measure three microseconds for those twelve clock ticks (T-states <which is EXACTLY how long a 1 MHz 6502 takes to do that. Hence, I conclud Exactly my point. The 6502 is not faster, it only marches to a different drummer. <I've concluded that most code I've seen underutilizes the internal resource <and overutilizes the external ones. Code like that favors processors with <more time-efficient use of the external resources. Hence, my assertion tha <there's reason to believe the 6502 at 2 MHz could outrun the 4 MHz Z-80 in <more or less typical code and in a more or less typical hardware No again. It can match the z80 and in some cases it's better or worse. <environment. Code written to make better than average utilization of the <internals of a Z-80 might fare better against equally well-written code on <6502. I'm comfortable with the reality that I'll probably never know for <certain. Since neither processor is particularly important these days, no <terribly important to me either. Agreed well written code is essential for either to do useful work. <None of this is really worth getting all excited about because, by the way <in spite of its "better" performance, (by my assessment) the 6502 didn't <accomplish more useful work on MY behalf, because I used a Z-80 running CP/ <every chance I got due to the abundance of really decent tools and office <automation software. Therein lies the key. A good system is not always defined by it's hardware. Systems are a combination of practical hardware and functional software. This account for why despite their flaws the TRS80, Apple II, Z80 CPM based as well as others florished. Most people didn't program 8080z806502ti990018028085680980886800065815 they ran basic or a word processor. the run on of part numbers was deliberate as to most people the cpu used was just a number. Allison

27 years

IBM 5181001 Printer available

by manney＠hmcltd.net

I have an IBM 5181001 "IBM Compact Printer" available. Includes instruction manual. Seems to take roll thermal paper (possibly FAX; although -- knowing IBM -- probably not.) Parallel interface. Anyone interested? P Manney Is it illegal to yell "Movie!" in a fire station? Thousands of discounted photo items at http://www.hmcltd.net/pgphoto

27 years

Sigh. Bringing up a PDP-8/M

by cmcmanis＠mcmanis.com

Dontcha just hate it when this happens? Here I am happily working away on an 8/E chassis with boards scavenged far and wide to get it up and running. In the course of which I'm using boards out of my 8/M that works find to replace questionable boards to reduce the number of variables in the equation. So the 8/E (with an 8/F front panel) is all up and running with my hodge podge of boards and I reassemble the 8/M, turn it on and the 'RUN' LED is stuck on. No response from the front panel halt switch state. Argh! --Chuck

27 years

VERY OT: Win'98 splash screen

by roblwill＠usaor.net

Hi! I know that this is WAY off-topic, but I need some help: While "cleaning up" some files on his computer my dad accidentally deleted the "LOGO.SYS" file. Now when he has no splash screen when booting. All that's shown is the startup commands and the BIOS settings of the computer. He wants me to fix it, but the only problem is that he doesn't have the Windows '98 CD (came pre-loaded on the computer). What I want to know is if anyone running Windows '98 could email me the logo.sys file (I think it's only 120k or something close to that). ThAnX! -- -Jason Willgruber (roblwill(a)usaor.net) ICQ#: 1730318 <http://members.tripod.com/general_1> PS>> Please remember to change the email address to mine - this doesn't need to be continued on the List....

27 years

FREE: Vic-20

by fpp＠concentric.net

Hi Anthony, I am looking forward to receiving the Vic 20. I was wondering if you have sent it yet? I had to respond to the list as I don't have your personal email. >Wow, I have always wanted a vic20. If you still have it I'd love it. I have >several Apple IIc if youd like one. No thanks. Trying to reduce the amount of stuff. =-) Since you're the first to ask for it, it's yours. If you want it, send a check for $7.50 to Anthony Clifton 407 E. Porter Avenue Des Moines, Iowa 50315 and I'll ship it out to you by the fastest route that costs $7.50 or less. =) Thanks! Also, send me your shipping address for USPS shipping. Anthony Clifton - Wirehead

27 years

Hallelujah!

by max82＠surfree.com

I've finally gotten around to reading a LISP book that I had bought months before, and I can see why people refer to LISP as a religious experience (I've seen that said at least twice). It's really a wonderful language. I wonder how it is worse than BASIC or Perl. Also, although I didn't really take the time to really understand smalltalk (Squeak is slow and unstable), I can see the beginnings of smalltalk in LISP. Wow. This thing really is pretty amazing. This should be taught in every computer programming course, along with PAL-8, C, and Perl. I am now certain that if a language is hard to learn (C++ comes to mind), there's something wrong with it :) --Max Eskin (max82(a)surfree.com)

27 years

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test-drb April 1999