test-drb September 2004

test-drb@ccmp.vtda.org

268 participants
648 discussions

Book available -- "The Computer Technician's Handbook" -- Computer Automation PDC 808

by wmaddox＠pacbell.net

I have a duplicate copy of "The Computer Technician's Handbook", by Brice Ward, TAB No. 554, 1971. The first half of the book is a convetional treatment of basic digital logic theory, logic families, and such, with an emphasis on the 8200 series. The second half of the book is more interesting. It is a "case study" of the Computer Automation PDC 808, complete with a description of the architecture, logic diagrams, a detailed walkthrough, timing diagrams, scope waveforms, etc. Much of it looks like it was probably lifted from the manufacturer's service manuals. The PDC 808 was an 8-bit minicomputer (yes, 8-bit) introduced in 1968. It appears to have a family resemblance to the 16-bit PDC 816, and more closely resembles the traditional 16-bit "stretched PDP-8" minicomputer style rather than most of the later 8-bit architectures seen in microprocessors. The bookseller rated this book in "very good" condition. It is clean with a tight binding, with some wear on the cover and a small crease. I paid $7.00 for it. I'll sell it for that plus shipping. --Bill

21 years, 1 month

Northgate Laptop Question

by opinion102＠hotmail.com

Hey, I ran accross one of your newsgroup posts on the internet the other day. I bought a northgate ZX off Ebay, and have found it difficult to find the A/C Adapter, can you give me any advice to locate one for sale, or perhaps where to buy the connector, so far, It seems nobody has anything compatible which would power the computer. Now I guess I know why the guy selling it was so eager to get rid of it, lol.... Thanks for your help, Michael _________________________________________________________________ Don’t just search. Find. Check out the new MSN Search! http://search.msn.click-url.com/go/onm00200636ave/direct/01/

21 years, 1 month

Made first phone call

by marvin＠rain.org

I think Sellam absolutely did the right thing!!! A number of people here in Santa Barbara have passed away with significant classic computer related items. For one example, many of the IBM 1130 and Burroughs manuals that Al has scanned came from someone who had worked with these things for close to 40 years. *ALL* of those manuals were destined for the recycle bin. The only reason they got saved was a friend of mine called me after he saw them when he was picking up other equipment there. I called his wife and was invited to come over and take what I wanted (I took everything!) When I saw her again a couple of months ago, his wife was very happy to hear that they have proved useful to others. A friend of mine passed away many years ago, and I was called to see if I would help with the stuff. He had been involved with microcomputers >from the first, and his father knew nothing of the value of this stuff. Of course, at that point in time, a lot of classic stuff was still deemed junk and went to that great storage space in the sky. Out of that came an almost complete set of (can't remember the name right now) cassette programs for the TRS-80 that were mailed out on a subscription basis along with many of the docs and associated correspondence (he was also an editor for a bit.) There were also boxes of documentation for other now classic computers. There are many such stories by myself and others on this list. I don't know where you and your wife are coming from, but the main focus of most of us on this list is saving classic computer related hardware, software, docs, etc. And many of us have irreplaceable items as most likely Don did. Again, Sellam did the right thing, and I am reasonably sure it was also what Don would have wanted. > On 19/09/2004 Sellam Ismail wrote: > >I made an initial phone call to Don's number and got an answering machine > >(presumably Don's voice is still on the OGM). I chose not to leave a > >message. I'll try again later today. > > Sellam, I'm shocked by your lack of tact and respect. No matter how > important Don's collection might be in your eyes, you shouldn't lose > sight of the fact that his wife and family have just lost him. They > probably couldn't care less about what happens to his stuff in the > garage at this point. > > I've asked my wife for her opinion on this and she said that she > would instantly scrap and toss my stuff if she ever found herself in > a similar situation. I can't blame her. > > What do others think of this ? > > Greetings, Jos

21 years, 1 month

5.25 fdd drive

by mattd1205＠sbcglobal.net

hello i have the teac floppy drive and it has does not need any driver. email me if u need any more info matt

21 years, 1 month

78MGT2 and 79MGT2

by rvtechno＠vsnl.net

Hi there I saw your posting. I think I know where I can pick up these Regulators. Do you have the datasheets / pinouts so that I can test them? Venkat VU2KV

21 years, 1 month

PING Ed Sharpe

by jpl15＠panix.com

Please contact me privately *off-list* - thank you. Cheers John

21 years, 1 month

Paul Kondig and Jerome Fine and others- collector's list

by mahoneyb＠gmail.com

A short update on the collector's list which I maintain here : http://www.geocities.com/computercollectors/ (Paul and Jerome, if you read this, I need your current email address as the ones I have keep getting bounced.) If other collectors want to be on this list, check it out to see if it is in a format you wish to be associated with, and email me here : antiquecomputers(a)hotmail.com Don't reply to the list or to this address (I'll miss it) with a complete listing of your address, email, phone number (if you want) and list of interests in the computer collecting area. Thanks. We now return you to our regularly scheduled programming. BM

21 years, 1 month

Relay computers

by avickers＠solutionengineers.com

At 22:50 23/09/2004, you wrote: >On Wed, 2004-09-22 at 11:17 -0700, Vintage Computer Festival wrote: > > On Wed, 22 Sep 2004, Jules Richardson wrote: > > > > > Apologies if someone's mentioned this one before. Quite possibly the > > > coolest gadget I've seen in a long time, though: > > > > > > http://www.cyberniklas.de/pongmechanik/indexen.html > > > > Awesome. It would be great to get stuff like this exhibited at the VCF. > > > > The web page is pretty smart also. What terrific technical and design > > work. > >Amazing, huh? If I read that right, it's 52 relays though (I don't know >any German) which makes it sound rather like a 'simple' relay control >system rather than an actual relay computer. I fired off an email to >them to see if they'll let me have a nose at the wiring diagrams. I did some back-of-a-fag-packet calculations (i.e. they might be completely & utterly wrong, in which case I'd appreciate corrections) on a relay computer... Assume you want a Z80-type CPU. This has ~8k gates. Typically, it seems to take 1 relay per input to implement any given gate. Now, I don't know how many "x-input" gates there are in a Z80, so I'll assume that - on average - it will require 3 relays/gate. Thus, we need ~24,000 relays to implement the Z80. If each relay needs, say, 25mA @ 6v to operate, then the peak current draw of our R80 (as I shall call it) could be around 600A (I think). And that's before we've added memory, i/o, etc. As for the heat/noise - well, IMHO it's worth building it just to experience that! Mind you, you'll need a lot of room: If you use 30mm by 13mm relays, then the board space you need is at least 9.36 square metres... Still, if you assume that each board needs approx 40mm of space incl. airflow room, then you should be able to fit the R80 into 2 400mm by 400mm by 2000mm cabinets (internal w/d/h)... The relays I've been looking at typically quote around 25ms to operate (either way), so I don't see how you could clock the R80 at anything faster than around 40Hz; and you'd probably want to drop to 20Hz to be on the safe side. The same relays quote a typical lifetime of 10e7 operations; so at 20Hz, your R80 should last a little under 139 continuous hours of operation before relays started failing... Creating a screen driver should be interesting.... Question: Wouldn't it be easier to implement an OR gate with no relays at all (just two wires joining together)? Or would you need to use the relays to keep the output voltage/amperage regulated? Additional: Hunting around for a suitable CPU to implement in relays, I came across the P8 CPU design (http://www.rexfisher.com/P8/P8_TOC.htm). This uses a 74LS181 4-bit ALU, which I reckon would require 149 relays to replicate. The only thing that confuzzles me is: what use, exactly, is a 1-input AND? Several of these appear on the 74LS181 schematic... Cheers, Ade.

21 years, 1 month

1892 calculator on epay

by mcesari＠comcast.net

This looks neat. This guy also has a 1920's "addometer" and a 1890 Stephenson adder. http://cgi.ebay.com/ws/eBayISAPI.dll? ViewItem&category=1247&item=2272912817&rd=1 I'm not affiliated with seller. Mike

21 years, 1 month

Pong pong pong...

by julesrichardsonuk＠yahoo.co.uk

Still on my Pong trip, here.. :-) Can anyone tell me how the original Atari arcade Pong (and probably the home version too) interacted between the bat and the ball? (Anyone got one they can hook up and try?) I've found one reference that says the bats were split into 8 segments; but when the ball hit the bat, was the resulting direction of travel influenced *only* by the bat segment hit, or also by the direction of travel at the collision point? Presumably if the ball hits the bat at the nearmost end, then the ball is returned in the exact opposite direction (i.e. reflected back along its path by a simple reverse of direction). But what about the other 7 positions? cheers, Jules

21 years, 1 month

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test-drb September 2004