test-drb October 1999

test-drb@ccmp.vtda.org

216 participants
748 discussions

SGI Hardware Developer Handbooks available

by pete＠dunnington.u-net.com

On Oct 7, 22:44, Pete Turnbull wrote: ...a message he should have sent to the original author, not the list. Apologies for the noise. -- Pete Peter Turnbull Dept. of Computer Science University of York

25 years, 2 months

SGI Hardware Developer Handbooks available

by jfoust＠threedee.com

I've got two of these available at no charge to anyone who wants them. They describe the pin-outs, etc. of the internal and external connectors of the SGI line from the 4D through the rest of the line up to about 1995. They're about an inch thick, spiral-bound. - John

25 years, 2 months

Mostek MK4027N

by ethan_dicks＠yahoo.com

--- Lawrence LeMay <lemay(a)cs.umn.edu> wrote: > Does anyone know how many memory bits are in a Mostek MK4027N? Its > also labelled S7748A. > > I'm guessing its either 4K x 1, or 16K x 1, which would mean the > pdp8/a memory board I have is either the 32K or 128K model. AFAIK, it's 4Kx1. The 128K board is hex-wide because it uses the fifth edge for extra address bits (along with the KT8A for control). -ethan ===== Infinet has been sold. The domain is going away in February. Please send all replies to erd(a)iname.com __________________________________________________ Do You Yahoo!? Bid and sell for free at http://auctions.yahoo.com

25 years, 2 months

Mostek MK4027N

by edick＠idcomm.com

The MK4027 is a 4K-bit DRAM organized as 4Kx1. Dick -----Original Message----- From: Lawrence LeMay <lemay(a)cs.umn.edu> To: Discussion re-collecting of classic computers <classiccmp(a)u.washington.edu> Date: Thursday, October 07, 1999 12:53 PM Subject: Mostek MK4027N >Does anyone know how many memory bits are in a Mostek MK4027N? Its >also labelled S7748A. > >I'm guessing its either 4K x 1, or 16K x 1, which would mean the >pdp8/a memory board I have is either the 32K or 128K model. I suppose >it could be 2K x 1 as well (there are only 3 ram sizes for this >board). > >-Lawrence LeMay >

25 years, 2 months

Mostek MK4027N

by lemay＠cs.umn.edu

Does anyone know how many memory bits are in a Mostek MK4027N? Its also labelled S7748A. I'm guessing its either 4K x 1, or 16K x 1, which would mean the pdp8/a memory board I have is either the 32K or 128K model. I suppose it could be 2K x 1 as well (there are only 3 ram sizes for this board). -Lawrence LeMay

25 years, 2 months

S-100 Bus

by edick＠idcomm.com

Your comments are interesting and probably correct, but I think you've missed the point. What I wanted to address is the problem of deciding which features to put into a tool and which ones to leave out. The issue of host speed is interesting, except that it really doesn't matter whether it can emulate the S-100 system's processor at 15 times its normal rate or 2500 times its normal rate. The interface is bandwidth limited by design to 2 MHz updates. I've contemplated a FIFO of some sort, but since the S-100 can be operated in bursts or in loops at an arbitrarily high speed anyway, I doubt there's a need for a FIFO. What boards there were or are isn't really relevant, since the target is to produce a useful tool. Pointing out the weaknesses, which, after all this time are either forgotten by or known to all of us, of one tool or another, won't help. What I'm addressing is using TODAY's technology to facilitate testing and verification of the S-100 bus. We're free to assume that the width of various signals can be adjusted in 10 ns increments just to determine what might work the best, even if the CPU can't really generate that waveform, and we're free to try solutions to the S-100's 7 equations in 4 unknowns, not only as a linear programming problem, but with discrete attempts with each possible solution, even though our CPU doesn't play that way, just to find out what really is wrong. This stuff is, in some cases, over 20 years old. Digital circuit design has evolved considerably since the '70's and, as it happens, much of what was sold on the S-100 market really didn't work, not because it was designed back in the '70's, but because it was designed badly. Some of it worked, "sorta," when in combination with specific other components (boards) but others didn't really work reliably, (e.g. survive a 1k-hour test/burn-in) under any circumstances. Unfortunately, sometimes the very circuits we wanted to use were in this category and wouldn't work with OUR hardware, even though it seemed to work fine with THEIRs at the store/trade-show-whatever, where we first saw it. What I would do if now were then is try a board in my existing test system to see if it caught fire or did something equally irksome. If it worked, I'd smile and proceed, and if it didn't, I'd attempt to find out why. If the board is claimed to be IEEE-STD-696 compliant, I'd try driving it with a '696-compatible set of signals to see if it behaved as expected. If yes, then I'd have CPU issues to resolve, not "new-board" ones. The tool I've essentially proposed enables you to do that without having to buy '696-compliant boards, since you can't readily pick up the phone and order them. It will, however, support you in an effort to whittle at each of the boards you want to use in order to make them work and play well with the others you wish to use, regardless how recalcitrant. Features I've already built in include the abilities you mentioned, examine and deposit memory content, easily extended, by the way to ensuring that the memory works consistently, stop the processor, single-step through execution of a program or cycle, jam an instruction onto the bus during an instruction fetch, etc. What's more, it can do this without a CPU in the system, or, assuming the CPU can do this, it can float the CPU and do "correctly" what you think the CPU is doing incorrectly just to ensure the fault is on the board you think it is. Anyway, people who've had the experience of bringing up a dead multi-board system in which the various manufacturers had no convention as to defaults or operating modes, in which it was a given that three or five boards, though all functional could and usually did yield a system which did nothing until the incompatibilities were ironed out, and in which there were no guarantees that ALL the components would work together at all, would have a really good idea of what features a generalized emulation/troubleshooting tool like this one should have. Resurrecting a 20-year old S-100 is VERY different from bringing up an old PDP-8. In the latter case, the bus standards were set by DEC, who knew what they wanted to put out there. In the S-100, boards were often designed by people with incorrect and/or incomplete information about what had to be on the bus in order for it to work correctly. They were virtually always designed with incomplete information about how other mfg's boards behaved on the bus. What's more, that behavior was likely to change, depending on how the CPU or other bus masters behaved. Since it's difficult to get detailed information about how a board you just bought at the flea-market works, you have to figure that out for yourself. This is a tool for doing that. It won't do it automatically but it will help you. Dick -----Original Message----- From: allisonp(a)world.std.com <allisonp(a)world.std.com> To: Discussion re-collecting of classic computers <classiccmp(a)u.washington.edu> Date: Thursday, October 07, 1999 7:03 AM Subject: Re: S-100 Bus >> on the MULTIBUS-I. The only case in which I've used a front panel has been >> the one MULTIBUS-user-client I had once whose SW types thought it would >> help. I doubt that it did, but it was a fun job! > >All the multibus bring ups were done using CPUs like intel 80/20 or >national BLC204, even if the bus was a mess you could run with these >as ram/rom/io on board were alive. > >> I agree, except that I belive that your PC-compatible would make an even >> better FP substitute, with its nearly 1 GHz processor, 1GB of RAM and > >Not to say it can't. The SBC880 was a z80/serial/parallel/rom/ram on one >card and more of less had those function isolated from the bus. This >allowed severly crunched bus to be driven while having the luxuray of a >real cpu and terminal interface. I used my own debug monitor in Eprom. >The key is I still have it, and I used it from the early 80s on. > >For board level debug the explorer 8085 <netronics> was good as s100 was >the 'add on bus" so if the card was not running you could >drive/interrogate it. > >> several 3-doz-GB HDD's. Moreover, since it can not only load programs and >> monitor their execution, clock-tick-by-clock-tick, and disassemble >> unfamiliar code in real time, generally waiting for the resident processor >> to catch up, it has potential not yet exploited. You can use it for logic >> analysis, signature analysis/failure detection, code verification, >> profiling, etc. It's just another tool, but if it can be sold for less than >> IMSAI's FP, then it's not only an improved tool, but less costly, too. >> Since you can repetitively stimulate the S-100 in a short loop, you can >> easily address signal quality issues previous too slippery for most folks. >> You can look over the processor's shoulder or you can take him out of the >> loop and run things yourself. When you've narrowed the problem you have >> down to a small set of signals, you can poke around with your 'scope to see >> that all's as it should be. > >A s100 card with z80, io and enough ram and rom to run is a trivial board >and was cheap even in the early 80s. Using todays parts 64k of eprom, >64k (or more) of banked ram and other things would be not only simpler but >cheaper too! > >The PC approach depends on the processor having lots of speed. What if >all you have for this kind of task is a 486dx/33 or maybe an old P133? >Not evey one is invested in PCs to the ears. FYI: my hottest PC is for on >line use and not for adding cards like that and it's only a P166 with >about 2.1gb. The only systems I have with an abundance of loose storage >are VAXen. > >> I never used a front panel until I was asked to build one for a >> multi-processor system on a VERY extended Multibus-I. That was fun and >> profitable, but wholly unnecessary, I felt, since all the processor boards >> were completely self-sufficient with the exception of mass storage, and >> since the CP/M image was in ROM, it didn't take long to boot, either. > >I started with PDP-8s, 10s then a CM2100 and firs micro was ALTAIR. FP >were ok for some thing where seeing state was nice. I used it more to mod >software that had IO that didn't match mine. It was the easiest way to >see what addresses it was looping at. > >> I've normally addressed lightning damage with a call to the insurance >> company, though they usually don't respond promptly. The procedure for >> socketed boards is to take the parts out and test them in a tester. Most >> prom programmers can do that. > >There were two proms in the entire system, 488 2102s, and lots of '367s, >241s, and '244s. Not to mention the fried terminal and printer. In 1979 a >logic tester for would have cost several times the system. Now, I'd toss >the MB <PC> and start fresh. > >> I really don't see how a logic probe can help you until you've narrowed the >> problem down to a single board. What's more, it's common enough to have >> several boards which work correctly in a system that doesn't. Sometimes >> they just don't work and play well with others. CompuPro boards were famous >> for this. They often wouldn't work with other boards from CompuPro. They >> weren't alone in this, but their idea of interoperability was that MOST of >> the boards in a system which they sold would work together. Their excellent >> marketing and advertising made them the main force behind adoption of a >> standard too weak to work, and too vague to provide guidance. They, more >> than any other maker of S-100 stuff ignored whatever parts of the standard >> that it suited them to ignore, and they weren't alone. The problems of this >> sort are exactly the sort I'd seek to address with a bus probe. What's >> more, there are few tools which will automatically allow you to find >> inadvertent connections between signals, say, because of a mis-jumpered >> board, or such, or to find that what one board maker uses for signal is GND >> to another. > >S100 was nice in one respect you could strip the bus and plug in pboard >until it broke. > >Allison > >

25 years, 2 months

Dangers of shifting classic computers (was: AT&T PC 6300 Plus Unix box) (fwd)

by af-list＠lafleur.wfi-inc.com

I guess my types of experiences fall into the categories of electric shock, muscle strains, smashed body parts, poison, and loss of sleep. I am not too bright. And I think of myself as sort of a tough, rugged, manly-man type of guy most of the time (hangover from playing rugby, I guess). Anyway, I have moved some things that should have required 3 or 4 people by myself (eg refrigerators, pool tables, etc) and really injured my back moving a Cipher 880 9-track drive a year or so ago. Agony! Not to mention being virtually useless for more than two weeks and having to go to physical therapy. I'm also generally too careless with electricity. I have been zapped by stupidly reaching into things and touching capacitors so bad that I've actually almost lost consciousness a few times. Now that I have a family I *try* to be more careful, but old habits die hard. I've broken a couple of fingers and toes by dropping things on them; it's amazing how much damage the hard, steel edge of a cabinet can do from just a few inches. My poison episodes have been dandies! The most recent was that black widow bite I posted about recently. The other was a *large* hp printer boxed in a wooden crate (recent model, 5si/mx with paper sorter, etc). When I removed it, I noticed that it was covered with some oily liquid. Completely dismissing this as somthing inert, I spend several hours working on it; sticking my head inside the cabinet, running my hands on it, eventually ending up with that oily liquid all over my hands, face, head, and I'm sure some was ingested from my hands/lips. Then I got sick. REALLY sick. Sick, like I wanted to die sick. It turns out that the guy who send it had sprayed poison into the crate to kill the wasps that had taken it over and neglected to tell us... Aaron On Thu, 7 Oct 1999, Peter Pachla wrote: > Hi, > > >....This machine will alwas have a special place in my collection > >though, since it is so heavy I sprained a muscle in my back while > >lifting it so bad that I needed several weeks of therapy to cure. > >One of the hazards of the old computer collector... > > Quite, I've managed to injure myself a number of times shifting medium/large > sized machines over the years. > > I trapped a nerve in my back both times I shifted my old PDP-11/23+ (in an > H960 cab with a pair of RL-01s). And please, believe me, shifting a PDP-11/34 > by yourself is NOT a good idea....my back muscles still wince at the thought. > > Also managed to strain a couple of back muscles when I moved my SGI 4D/70GT > into the house. There were two of us moving that beastie and we'd taken all > the boards out of it first (they're about the weight of my 11/53 on their > own). > > > Not to mention that I've been in agony for a week now with a trapped nerve in > my shoulder. But then again there really was no way to disassemble that "Space > Invaders II" machine which I was moving out of the house.... > > Anyone else hurt themselves, lost limbs etc??? ;-) > > > TTFN - Pete. > > -- > Hardware & Software Engineer. Sound Engineer. > Collector of Arcade Machines, Games Consoles & Obsolete Computers (esp DEC) > > peter.pachla(a)virgin.net | > peter.pachla(a)vectrex.freeserve.co.uk | > peter.pachla(a)wintermute.free-online.co.uk | www.wintermute.free-online.co.uk > -- > >

25 years, 2 months

SGI Hardware Developer Handbooks available

by jfoust＠threedee.com

I just tried to answer a question from someone on the Greenkeys mailing list, regarding interfacing an ASR-33 to RS-232. My answer is below. I hope I got it right. - John At 11:30 AM 10/7/99 -0400, Barry Hall wrote: >Hello John and Christian, > > I was referred to you by Don Robert regarding connecting an ASR 33 to a >Microcomputer RS232 Serial COM port. Any help you can give me would be greatly >appreciated. The ASR-33 usually has what's referred to as a "20 milliamp current loop" interface. It's not RS-232. You can buy converter boxes from places like <http://www.blackbox.com/>, like the one at <http://catalog.blackbox.com/blackbox/templates/blackbox/class13itemgroup598 guest.asp?param=95&ig_id=598&title=High%2DSpeed+RS%2D232%26lt%3B%26gt%3BCurr ent%2DLoop+Interface+Converter&related=>. There's an explanation at <http://telebyteusa.com/catalog/appnotes/a65a.htm>, <http://www.mouse.demon.nl/ckp/serial/cl.htm>, <http://telecom.tbi.net/data-if.html> and <http://www.bb-elec.com/techlibr.asp>. I'm sure someone has a web page with a homebrew conversion between current loop and RS-232. The voltage levels and swings aren't the same, so it's not just a matter of wiring. The circuit at <http://www.ibhsoftec.de/english/screenshots/current_loop_converter.html> might be right. - John

25 years, 2 months

Running a 220v computer in a 110v environment

by Philip.Belben＠powertech.co.uk

> The only safe way is to use a transformer that is correctly wired. US mains is > 120 - neutral - 120. which gives 240 between the 2 hots. European mains are > 240 - neutral. Both expect the neutral to be at / near ground potential. If > you wire it to US 240 directly what was neutral in Europe will be at 120v. I > have several isolation / step up transformers that I routinely use to accomplish > this. You need to be careful how they are wired in order to have both primary > and secondary tied correctly to neutral and the grounds MUST be kept separate > from the neutral to meet US electrical code. In Europe, many outlets (German ones spring to mind) are mechanically symmetrical with respect to swapping hot ("Live") and Neutral pins, and AFAIK all equipment has to be able to operate whichever side of the input is earthy (=close to ground potential). I would have no qualms at all about running European equipment of 120 - 0 - 120, although for travel I have made my own autotransformer from a 100VA split-primary mains transformer. Some old (before about 1960) equipment bonds neutral to equipment chassis. This is of course dangerous to run except with the correct side earthy. I have heard rumours of German equipment with a neon between chassis and earth that lights up if you get this wrong! When wiring a step-up transformer: Single winding (autotransformer) should have neutral one end, 120V in the middle and you get 240V out of the other end. Ground (earth) goes straight through without connecting to the windings. Dual winding (isolating transformer) Input across Neutral and 120V - output gives you 240V. Bond one side of the output to Ground, NOT neutral, and this becomes the new neutral [*]. This ensures that a fault to the chassis is guaranteed to trip earth leakage protection downstream of the isolation transformer (which I doubt you have) but not upstream of it. This is much safer if (for example) hot and neutral are reversed on the input. (Note: if you wire one side of the output to neutral, you have something no worse than the autotransformer.) I don't know whether this latter meets the US electrical code, but it is correct :-) As regards strange sockets, I don't imagine 3-phase would be at all likely in a US domestic installation, but 220V happens occasionally. The usual plug is just like the standard US 3-pin plug, but with the two flat pins at 90 degrees to their familiar position. This can roughly be represented in ascii-art thus: o o 120V _ _ 220V | | DEC used it on a lot of their European equipment... Philip [*] For full isolation, don't link ground on the two sides of the transformer. Link chassis etc. on the output to the virtual ground terminal that's bonded to the supply rail you've chosen as neutral. This means that you have to touch both a hot wire _and_ the chassis befor it will zap you. For some testing, don't bond at all - you can't detect a fault to chassis, but you need a fault _and_ to touch the wrong wire before you get a shock... Some more ascii-art, for the record. Autotransformer: ________ 240 C C 120 ____C C C N ______C_______ N Isolating Transformer wired as Autotransformer: _____ 240 ||C ||C 120 _____||C C||C C||C N ______C||C____ N |____| Isolating transformer: _____ 240 ||C ||C 120 _____||C C||C C||C N ______C||C____ N - Bond this to earth and/or chassis as necessary ********************************************************************** This email and any files transmitted with it are confidential and intended solely for the use of the individual or entity to whom they are addressed. If you have received this email in error please notify the system manager. This footnote also confirms that this email message has been swept for the presence of computer viruses. Power Technology Centre, Ratcliffe-on-Soar, Nottingham, NG11 0EE, UK Tel: +44 (0)115 936 2000 http://www.powertech.co.uk **********************************************************************

25 years, 2 months

Current Loop Converter

by daniel＠internet.look.ca

ftp://ftp.bb-elec.com/bb-elec/literature/232pclin.pdf This is the full schematic of an industrial one. I built one with two transistors years ago.. I will dig up my design and post it (used it on a DG-116) -----Original Message----- From: John Foust <jfoust(a)threedee.com> To: Discussion re-collecting of classic computers <classiccmp(a)u.washington.edu> Date: Thursday, October 07, 1999 2:23 PM Subject: SGI Hardware Developer Handbooks available > >I just tried to answer a question from someone on the Greenkeys >mailing list, regarding interfacing an ASR-33 to RS-232. My answer >is below. I hope I got it right. > >- John > >At 11:30 AM 10/7/99 -0400, Barry Hall wrote: >>Hello John and Christian, >> >> I was referred to you by Don Robert regarding connecting an ASR 33 to a >>Microcomputer RS232 Serial COM port. Any help you can give me would be >greatly >>appreciated. > >The ASR-33 usually has what's referred to as a "20 milliamp current loop" >interface. It's not RS-232. You can buy converter boxes from places >like <http://www.blackbox.com/>, like the one at ><http://catalog.blackbox.com/blackbox/templates/blackbox/class13itemgroup59 8 >guest.asp?param=95&ig_id=598&title=High%2DSpeed+RS%2D232%26lt%3B%26gt%3BCur r >ent%2DLoop+Interface+Converter&related=>. > >There's an explanation at <http://telebyteusa.com/catalog/appnotes/a65a.htm>, > <http://www.mouse.demon.nl/ckp/serial/cl.htm>, ><http://telecom.tbi.net/data-if.html> >and <http://www.bb-elec.com/techlibr.asp>. > >I'm sure someone has a web page with a homebrew conversion between >current loop and RS-232. The voltage levels and swings aren't the >same, so it's not just a matter of wiring. > >The circuit at ><http://www.ibhsoftec.de/english/screenshots/current_loop_converter.html> >might be right. > >- John >

25 years, 2 months

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test-drb October 1999