- vcf-midatlantic - lists.vcfed.org

Re: [vcf-midatlantic] GTE XT 300 - Information
by jsalzman＠gmail.com 15 Jan '22

15 Jan '22

If they just scanned the document today, then it won't be available for download until tomorrow at the earliest. On Fri, Jan 14, 2022, 7:36 PM skogkatt007--- via vcf-midatlantic < vcf-midatlantic(a)lists.vcfed.org> wrote: > OK. CHM was able to find the manual and now it is online: > https://www.computerhistory.org/collections/catalog/102638857 > > No option to download, unless I'm doing something wrong (a given :). > > >

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GTE XT 300 - Information
by Jeffrey Brace 15 Jan '22

15 Jan '22

Someone is looking for information on the GTE XT 300 computer. Here is an ad for it: https://drive.google.com/file/d/19OfZY5biuA4acft4Y5jQdt8uakpPsm-d/view?usp=… If anyone has any more info, then please let me know. Thanks! ========================================= Jeff Brace VCF National Board Member Chairman & Vice President Vintage Computer Festival East Show-runner VCF Mid-Atlantic Executive Director Vintage Computer Federation is a 501c3 charity http://www.vcfed.org/ jeffrey(a)vcfed.org

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Add-on card edge fingers for mock S-100 boards
by Herb Johnson 14 Jan '22

14 Jan '22

> Jonathan Chapman > > retrobrewcomputers.org > > Their boards are high-quality modern production with proper hard gold edge plating ... It wasn't clear if they (Goodman) is offering what they call "unbuffered" or "plain" S-100 prototype boards. The buffered board is apparently expected to be memory or I/O, not a processor board or bus-controlling board such as a new-designed 8080 board as Joe Giliberti may be considering. And without detailing the differences, there's different flavors of S-100 bus; Joe may desire the earliest kind for IMSAI/MITS operation. Prices at "auction" for old-stock S-100 prototype boards with no layouts, as old stock commercial products, seem to be in the $25-$50 range plus shipping. The newly produced bare boards at retrobrew, seem to be in that range also. The cheapest possible least-desired old S-100 cards touch that range also, as I've observed. Thus I'd call that range "the bottom" for S-100 boards of any sort. And it's hard to find S-100 connectors below $10 a pop, for that matter, they are often more. It's not appreciated, that S-100 PC mount connectors came in two pin-widths between the two rows. Different brands of backplanes used one or the other. It's a gotcha to buy the wrong width connectors for a particular unpopulated backplane. So much for "standard" S-100. ;) Regards, Herb Johnson -- Herbert R. Johnson, New Jersey in the USA http://www.retrotechnology.com OR .net preserve, recover, restore 1970's computing email: hjohnson AT retrotechnology DOT com or try later herbjohnson AT comcast DOT net

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S-100 protoboards
by Herb Johnson 14 Jan '22

14 Jan '22

>> It's not appreciated, that S-100 PC mount >> connectors came in two pin-widths between the two rows. Different brands >> of backplanes used one or the other. It's a gotcha to buy the wrong >> width connectors for a particular unpopulated backplane. >> >> Regards, Herb Johnson > > It was my understanding that only the Altair backplane had a different row > spacing for it's connectors. Everything that I have seen since (IMSAI, > Ithaca, TEI, CompuPro, Cromemco) used the same .250 row spacing. > > Regards, Jeff Well, maybe I didn't state the situation clearly. It takes a little longer to do so, I didn't want to go off on details, on side issues to another topic that has already ended. So I'll make a simple point. There's all kinds of 100 pin connectors one might buy, which won't likely be labeled "S-100". You have to measure the pin spacing anyway - which for all S-100 cards is 8 pins per inch. .125 inches apart. So you may as well, check *your particular motherboard* that you are buying connectors for, *just* to be sure the the particular connectors you are buying, match the pin row-width also. That will be, whateverthehell it is, because there were any number of S-100 card-producers, who made backplanes, with whatever connectors they purchased. Just check all your measurements, to avoid getting the wrong part. That's all I was saying. It's factually been a problem. Regards again, Herb -- Herbert R. Johnson, New Jersey in the USA http://www.retrotechnology.com OR .net preserve, recover, restore 1970's computing email: hjohnson AT retrotechnology DOT com or try later herbjohnson AT comcast DOT net

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Minerva's Machine - women and computing
by Herb Johnson 14 Jan '22

14 Jan '22

> George Washington University has it in their library which is over in the > City. West Chester PA has it, WVU. One in Allentown as well. > > If you can't find it anywhere I might be able to reach out to GWU about > what it takes for a non-student to check it out ... There's something called "inter-library loan" that most local public libraries and universities support. Typically your local tax dollars pay for the library services you get (once you register). Contact your local library system for details. They will perform the loan request, obtain the item for your pickup, and return it when you return the item to the local library. Regards, Herb Johnson -- Herbert R. Johnson, New Jersey in the USA http://www.retrotechnology.com OR .net preserve, recover, restore 1970's computing email: hjohnson AT retrotechnology DOT com or try later herbjohnson AT comcast DOT net

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Minerva's Machine - women and computing
by Jeffrey Jonas 14 Jan '22

14 Jan '22

In 1995, the ACM (Association for Computing Machinery) and others funded a documentary: Minerva's Machine: Women and Computing. The Amazon VHS is out of stock. Is there any other copy or reference?

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My current inventory
by Joseph Giliberti 14 Jan '22

14 Jan '22

Greetings! First off, I apologize if I'm flooding the list with my project so say the word and I'll try and condense things. Based on feedback from many of you, I've decided to start off in the form factor of a single board computer. Once the basic machine is running, I can start thinking about expansion. Here are my basic plans for the system: - The computer will be constructed on the prototype board offered to me by Bill Dudley - Basic I/O will be via hexadecimal keypad and numeric display. This will likely mount as a daughter board on top of the prototype board, leaving clearance for components underneath and connected via a ribbon cable - Contained in ROM will be a machine language monitor and some version of TinyBASIC - The machine will have either four or eight kB of SRAM - The machine will have an audio cassette interface utilizing the Kansas City standard for program storage - The machine will have either a serial or current loop interface for communication with a video terminal or teletype Once the machine is established and I am comfortable with it, I can move on to things like more RAM and a floppy disk controller. My current component inventory, not including TTL and passive components, includes: - (1)C8080A - (1)C8212 - (1)C8214 - (2)C8216 - (1)C8228 - (2)C8238 - (1)C8255 - (3)C2112A - (4)2716DC 2kx8 EPROM - (39)P2114 1kx4 SRAM At this point, I'll stay quiet for a bit and let other projects occupy my time, whilst continuing to study and gain knowledge. TIA Joe Giliberti

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changing my bus route
by Joseph Giliberti 14 Jan '22

14 Jan '22

Greetings! I was initially planning on setting up my mid-late 70's 8080 computer on wire-wrapped S-100 boards. However, I found that S-100 prototype boards are very expensive. Bill Dudley suggested I use a standalone prototype board that he had, but it has limited real estate for things like memory and disk control circuitry. It has an expansion connector, but it is a proprietary connector. After some research, I think I may have found the solution: Intel's Multibus. For one thing, wire wrap prototyping boards have more area and are readily available (and inexpensive.) A multibus power supply puts out standard voltages which do not require regulators on each card. Is this the ideal solution that I'm thinking it is, or am I overlooking something? TIA Joe Giliberti

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What IC Do I Have Here?
by Joseph Giliberti 13 Jan '22

13 Jan '22

Greetings! AY-5-4007A I actually have five of them. I'm assuming based on the part number that they were made by General Instruments. They are 40 pin 0.6 inch dual in-line units with a white ceramic case and not-gold pins. All five I have are dated the fourth week of 1974. I can find no references to this exact part number. There is a known AY-5-4007D, which is a 24 pin seven segment display driver. I would guess that a indicates the first in a series. Along that line, I'm thinking they might be bit-slice ALU chips, but that's just a wild guess. Regardless of what they turn out to be, I have absolutely no use for them, so let me know privately if you would like to take them off my hands. TIA Joe Giliberti

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changing my bus route
by Herb Johnson 13 Jan '22

13 Jan '22

[A lot of old-school tech chatter today!] Discussion of Multibus vs S-100 bus Joe apparently missed both Jeff's message about retrobrew computers, and my message on auction-site prices for S-100 boards. On price S-100 boards will be cheaper than Multibus (except collectables). I imagine he's caught up now. And a S-100 board of 5 X 10 inches is an awful lot of space. Multibus is about 6 X 12: whadda gonna do with either size? It's a lot of chips, especially modern chips. Jonathan makes the point: do something with something, then see where you go next. You don't have to start with your destination design, in fact it's advisable to start simpler and make your mistakes early. I'm relatively active in vintage Multibus. Certainly enough to agree with Jonathan Chapman's assessment of Multibus. It's a little more complicated than S-100 and IEEE-696. It can get a lot MORE complicated because these were used in complex industrial settings and industrial products (as were some S-100 systems). As David Guesswein suggests, there's not widespread vintage interests in Multibus, as those who worked on Multibus have aged-out of the vintage computing discussion. Also Multibus was an industrial product, whereas S-100 was both industrial and popular-computing in its lifetime. Essentially S-100 was the cheaper alternative to Multibus. Today there's a somewhat private Google group who have revived Intel-based Multibus development systems. https://groups.google.com/g/intel-devsys Otherwise a Web search may find various Multibus pages and sites with information (including mine). I'm not aware of all that many, but i don't engage much with many online discussion groups. If you find more activity online about Multibus, let me know! So discussion about Multibus that I'm aware of, quickly becomes discussions with engineers of decades of experience in programming or hardware design, about fairly busy systems that performed control or ran 20th century operating systems. I get intimidated, and I know some stuff. But the early bussed stuff - Multibus or S-100 bus or say STDbus - is approachable for the technically minded. Jon Chapman has revived the old OSI bussed systems and one 8080 multibus board. There's SWTPC, the SS-50 bus, with some revived new boards by corshamtech.com, that's a 6800 6809 classic bus. Busses get more obscure from there. There's many points of entry, for people who want to design up something at the vintage processor-chip level. and for each kind of "entry", there's of course people who have been there and know what's went on. But some of these are pretty complicated and busy, with lots of legacy stuff that can be intimidating or simply not of interest. Others are simpler: the single-board stuff was intended to be simpler and introductory. As I and others said: Joe, where you start may not be where you end up. There's good reason to make a few simpler things first, then more complicated things later. from the experience of doing so, you'll know what to look for and what's of interest to you in the next step. Put another way: I've had lots of people contact me (I have some reputation in the S-100 world) about their "ultimate S-100 system" who never got there. One reason may be, they didn't get enough prior experience on simpler systems or projects, and so were not able to "get traction" on critical S-100 concepts or complexities or about CP/M (the predominant OS for S-100). So they gave up. Regards, Herb Johnson -- Herbert R. Johnson, New Jersey in the USA http://www.retrotechnology.com OR .net preserve, recover, restore 1970's computing email: hjohnson AT retrotechnology DOT com or try later herbjohnson AT comcast DOT net

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