test-drb March 2008

test-drb@ccmp.vtda.org

209 participants
369 discussions

by wacarder＠earthlink.net

>By the way, the original wasn't written for Unix, though IIRC a ported >version did appear in the games directory in one or two BSD releases. >The original was written in BASIC in 1972-73, and the late Greg Yob (the >author) wrote a piece about which is in the BASIC Computer Games books. > My BASIC Games page has a machine-readable version at >http://www.dunnington.u-net.com/public/basicgames/ >Pete Peter Turnbull > Network Manager > University of York If anyone wants to play WUMPUS, I have it on my Wofford Witch system online. Just go to my web site http://www.woffordwitch.com, and log onto my system using the guest account 40,1. Once you've logged in, you can run WUMPUS by typing RUN GAME:WUMPUS at the READY prompt. If you want to see the BASIC PLUS listing, you can type OLD GAME:WUMPUS and then type LIST at the READY prompt. This version is from the early-to-mid 1970s. Ashley http://www.woffordwitch.com

17 years

6502 CPU schematics

by cclist＠sydex.com

On 10 Mar 2008 at 12:00, Ed Thielen wrote: > Greg Mansfield had KRONOS going, and shipping to some customers, > - mostly educational - by the time I left. > Greg was kind of a one man band - a bit of a Dilbert > - a remarkably imaginative and productive individual - Greg later left CDC (during the 1980's decline and fall) and went to Cray. He was an active microcomputer addict and at the time, had a pretty elaborate Compupro system, IIRC. I had the pleasure of introducing Greg to the wonders of gelato; I've lost contact with him over the years and am not aware of what he's up to. His compatriot in crime at Arden Hills, Dave Callender (sp?) was quite a character in his own right. "Dr. Dave" maintained an active interest in bats and had various specimens on display in his office. Greg's work with MACE would not likely have attracted any notice at CDC were it not for Dave. I was once told (but don't know if it's accurate) that he was a student of Harold Edgerton's and had suggested photographing bats using Edgerton's strobe--whence the great photos of the bats of Carlsbad Cavern originated. Perhaps someone can confirm this. Cheers, Chuck

17 years

6502 CPU schematics

by cclist＠sydex.com

> Date: Sun, 09 Mar 2008 14:50:55 -0400 Roy wondered about systems with various CPU options. What CPU did the Jolt system use? Was there more than one CPU option? Does anyone still have one of these? (basically a stack of interconnected PC boards) Cheers, Chuck

17 years

replacing "failed" components question: causal or coincidental repairs?

by lynchaj＠yahoo.com

Hi, I have been fixing an old WaveMate Bullet computer and have come across a question I thought maybe the CCTALK mailing list could answer. I apologize if this is an overly long post but it takes some explaining to get to the real question. When I bought this WMB machine it was completely dead. It had no response at all and the Z80 CPU was completely static except for the clock input on pin 6. I used my oscilloscope to debug the circuit. The PS checked out fine. On power up the floppy drive turned on and would seek to home but I think was more a "nervous reflex" of the MB8877/SY1793 FDC powering up and being selected rather than something the CPU was intentionally doing. No data was being read from the disk drive with a known good working boot disk installed. After finding some illegal voltage values on the address bus and some other fault isolation, I noticed that if I put my finger on the CPU, then it briefly went into a flurry of activity before crashing again. I isolated the illegal voltages on the address bus to just between two chips. After touching CPU with my finger caused something to happen, I suspected the CPU was bad or possibly a cold solder joint. As a starting move, I replaced the Z80 with a new socket and new CPU and made sure all the solder connections were good and thoroughly good. The good news is on the next power up the WMB booted and seemed to work just fine. However, I have two known good boot disks; the first is a partial CP/M 2.2 system (boot tracks plus minimal generic OS utilities from Gaby's site. It did not include any WMB specific tools like FORMAT) and the second is a complete CP/M 3.0 customized for the WMB. I know both boot disks are good since I have repaired another WMB and both disks work on that machine. Here is where things start to get strange... The CP/M 2.2 disk booted just fine. However, the known good CP/M 3.0 disks, even ones written using the boot drive (to eliminate alignment issues, etc) would "half boot" and crash just after printing some or all of the initial boot message. CPMLDR would execute but apparently CCP never got properly launched before crashing. So I spent a couple of days searching for what I presumed to be a hardware failure. The CPU seemed stuck in a polling loop and I could not find the "broken" part. I ended up finding some strange voltage values on the PIO and replaced it and a buffer chip but the strange boot behavior persisted. The CP/M 3.0 disk still refused to boot. I inspected the source for the CP/M 3.0 CBIOS and found what appeared to be possible places where it was hanging. Since I had already replaced the CPU with a socket and a new CPU I thought maybe the "new" CPU was having problems during the "enable interrupts" command immediately prior to the printing of the initial boot message. Sure enough, I replaced the "new" CPU with another one and the problem went away. The WMB now boots CP/M 2.2 and CP/M 3.0 from the boot disks like nothing was ever wrong. So to my actual question; how do I know that the CPU's were really bad and it is not something else being tweaked during the "fixing"? I can see one CPU failing and replacing it to fix the computer. However, finding TWO bad CPUs in a row is just highly suspicious to me. Maybe there is a sneaky cold solder joint someplace? I think repairing old computers is just like any human endeavor - it is flawed and sometimes I follow incorrect logic and/or misdiagnose before finding and fixing the real broken part. Sometimes good parts get mistakenly identified as bad. That's life and if a part falls under suspicion I am likely to just replace it just to test the theory, right or wrong it gives information and vital clues. Anything labeled "suspect" is pulled aside and labeled as bad regardless. These parts are cheap and plentiful enough that if a few good ones get trashed in the process of fixing an old machine I consider it a worthy investment. Probably I am tossing some good parts occasionally but it is worth it time wise to take the chance and maybe find the root cause. Were I more skilled technician maybe I could fault isolate with more precision and just fix exactly what is broken but this is just a hobby and I do not have the time/experience to get more precise. What is bugging me in this case though is whether swapping the two CPUs is actually fixing the REAL problem or just coincidentally doing *something* which is the making it work but not actually fixing the underlying problem. I am uncertain if my "repairs" are actually causal or coincidental. The good news is in the end if the machine works reliably it doesn't matter all that much but I'd sure like to know for certain what actually happened. Is there some method to verify a Z80 CPU or PIO is actually bad or not? I have seen 74LSxxx chip testers which apparently work pretty well but nothing that can test a Z80 CPU or other LSI type chip. Thanks in advance for any advice or constructive comments. Andrew Lynch

17 years

End of restoration of the early French computer SEREL ODP-505 (germanium CPU)

by pichotjm＠free.fr

hi, I spent my week-end to write a report on the restoration of the early French computer ODP-505. This computer is built with germanium transistors and has a core memory. I spent my monday to translate the job for you. You will find the result here: http://pichotjm.free.fr/Serel/ODP505/ODP505us.html For curious people: you can visit the entire site with http://pichotjm.free.fr/indexUS.html Visting http://pichotjm.free.fr/ will gives quite the same, but in French. More information can be found in French. You can find more pictures... Enjoy! JMP

17 years

ebay fee hikes and stuff

by dgriffi＠cs.csubak.edu

Some of you are aware of a big snit over recent changes by Ebay. If you aren't, the basic rundown is that beginning May 1, these changes take place: 1) Sellers are no longer able to leave negative feedback. 2) Final fees are hiked 67%. 3) Listing fees drop by a few cents. This is annoying (I'd like to use stronger words) people greatly and another boycott is planned soon. I'm pondering leaving Ebay if they keep this abuse of their customers (ie me). -- David Griffith dgriffi at cs.csubak.edu A: Because it fouls the order in which people normally read text. Q: Why is top-posting such a bad thing? A: Top-posting. Q: What is the most annoying thing in e-mail?

17 years

Computer History Museum Artifact Storage Open House

by charlesleecourtney＠yahoo.com

CHM had an open house today for its new artifact storage building. Some pictures can be found at http://www.flickr.com/photos/lee_courtney/sets/72157604065526114/ Enjoy! Lee Courtney

17 years

The Ford Museum computer display

by jbmcb1＠gmail.com

I visited the (Henry) Ford Museum in Dearborn, MI this weekend - first time in about a year. They had an interesting display on how technology affects culture, starting out with books and magazines, running through radio and television, up to personal computers in the 80's. They had a "typical teenagers" room set up - complete with an Apple IIc, 9" screen, and Imagewriter II. They also had an original Mac 128 or 512 behind glass, the home Pong machine, and a selection of electronic games like Mattel Football, the Tomy Tutor, the Wizard, and others. It was a neat display, if not a bit limited in breadth. The Ford used to have an awesome display of old telephone and telegraph equipment, including a complete turn-of-the-last-century switchboard from a small local exchange. They mothballed the whole thing, but the huge display on aviation they replaced it with is pretty neat. They also had a large antique steam engine operating on compressed air for a while. It's pretty impressive seeing a 20' iron flywheel spinning using nothing but air.

17 years

Introduction and photos.

by mwichary＠gmail.com

Hey everyone, By way of the introduction I promised yesterday, I thought I will just share my various computer history photos... and let them speak for themselves. Photos from the recent CHM warehouse open house: http://www.flickr.com/photos/mwichary/sets/72157604083156622/ Other computer history museums: http://www.flickr.com/photos/mwichary/collections/72157603746061266/ Computer history events and miscellany: http://www.flickr.com/photos/mwichary/collections/72157603691109915/ Random photos from when I volunteer at the Computer History Museum: http://www.flickr.com/photos/mwichary/sets/72157603768627712/ Outside of volunteering and visiting various computer history museums/ events, I collect 8-bit Atari XL line (nostalgia), read tons of computer history books, and design computer history posters. Some of them you can find here: http://www.flickr.com/photos/mwichary/sets/72157603821017622/ Enjoy! Let me know if you have any comments/questions. -- Marcin Wichary Sr. user experience designer, Google Graphical User Interface gallery >> www.guidebookgallery.org Aresluna >> www.aresluna.org

17 years

CDC console

by ed＠ed-thelen.org

> Message: 20 > Date: Sat, 8 Mar 2008 21:18:32 -0800 > From: "Rick Bensene" rickb at bensene.com ... > Message-ID: B9639BAE3F34504E83FEEDD71D4AFB4615D8AB at mail.bensene.com > > The displays on the console were driven by a PPU (Peripheral Processing > Unit), which were small scalar processors (actually, one processor > multiplexed to appear as a number of independent CPUs), akin to small > minicomputers (like a PDP-8), which operated out of shared sections of > main memory. There was a PPU program that ran the display, generating > it from data in a section of memory. In SCOPE, PP # 10 was dedicated to this purpose - Each time shared PP (using a common adder) had its own memory of 4 K 12 bit words. This reduced the traffic to main memory. PP # 1 was normally assigned to monitor requests from the jobs assigned to "control points". A job would place a request in its relative memory location 0 for service by the system. PP # 1 would monitor these requests and assign other PPs to do the work, causing a PP to load a new program if necessary. I worked in CDC Special Systems from 1966 to 1971 - We shipped a version of SCOPE modified to run "Time Critical" which used modified code in PP #1 to guarantee user choice of - analog and discrete inputs - x milliseconds CPU time - analog and discrete output on a guaranteed time cycle - This was the best in the world at the time for doing hybrid computing :-)) which unfortunately was on its way out :-(( A system program to calculate resources to see if a new "time critical" user could be added to the running list. > The displays were vector only, not raster. Yes :-)) > There was dedicated hardware in the display console that did > CDC character set (a 6-bit code) conversion to vector characters. Not in any system we shipped, and we could run the "EYE" and Northwestern University CHESS program with another PP displaying the chess pieces in nice form on the right hand scope. The left hand scope being assigned to monitoring activity at the normally 8 "control points", showing activity and requests for operator intervention such as mounting/removing tapes and printer(s) out of paper... > Vector graphics were possible, within the limitations of the speed of > the PPU. Each PP had a 100 nano-second time sharing of the adder each 1 microsecond - hence a relatively hard upper limit of 10 PPs with out a special order for another 10 ( for customers such as Boeing). On later 6x00-series systems, such as the CYBER-73, the PPUs > ran fast enough to generate a nice looking all-vector chessboard on the > left screen, and a text-based transcript of the moves on the right > screen. There were also a number of other cute programs, one being a > pair of eyes (one on each screen) which would look around and blink. > The operating system was called KRONOS, and I clearly remember that the > console command to run the "eye" program was "X.EYES". Greg Mansfield had KRONOS going, and shipping to some customers, - mostly educational - by the time I left. Greg was kind of a one man band - a bit of a Dilbert - a remarkably imaginative and productive individual - I left CDC long before the CYBER-73 .... > > Rick Bensene > The Old Calculator Museum > http://oldcalculatormuseum.com Ed Thelen

17 years

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test-drb March 2008