test-drb October 1999

test-drb@ccmp.vtda.org

216 participants
748 discussions

Wanted: Mac 128K/512K schematics and service manuals

by Marion.Bates＠Dartmouth.EDU

Hi, You might've already tried this, but on Apple's site you can search the Tech Info Library Archives for older product info: http://til.info.apple.com/tilarchive.nsf/Web+Search+Simple If you do a search for Macintosh AND 128k it turns up a bunch of articles, some with fairly technical info (pinouts and such). Good luck, -- MB --- "John Lewczyk" <jlewczyk(a)his.com> wrote: I've recently acquired one 128K and one 512K Macintosh and am looking for technical documentation on it (schematics, logic diagrams of pc boards). I thought that it would be easy to find on the web, but I've had no luck after more than a week of searching. Any help with schematics or service manuals would be appreciated. I've found some pdf files that have some rudimentary diagnostic procedures: "if the logic board is bad, replace it" "if the floppy drive is bad, replace it". The 128K's floppy isn't working, even after cleaning the coagulated lubricant and I am trying to diagnose the problem. Thanks! John jlewczyk(a)his.com --- end of quote ---

24 years, 8 months

Designs (was Re: OT: how big would it be?)

by CLASSICCMP＠trailing-edge.com

>A SMT unit *might* be interesting... I can get all the PCBs done I want for >free (must have some kind of standard blocks) but the SMT building might be >difficult. Can the new pick and place machines handle TO-3s [not on tape]? I >am sure I can find a surplus lot of a few thousand NPN/PNPs for pennies. Sometimes the cheapest man ends up paying the most :-(. When you get to designs like this, you have to have some rational scheme for pre-testing your parts before you start stuffing giant PCB's. DEC was quite proud of their part and module testing machines, and with good reason! I'm pretty sure that Poly-Pak's main source of parts was the reject bins at DEC and DG :-). (I can't be the only one here who remember Poly-Pak, can I?) Tim.

24 years, 9 months

outgrowth of : OT: how big would it be?

by edick＠idcomm.com

So, who makes 256-byte RAM devices at TTL speeds these days. There are all sorts of FIFOs of 256 bytes, but I can't find a simple 256-byte RAM any more. I also need a 32x8-bit sram, fast (preferably address-access time <<10ns) and preferably in a small package. Dick -----Original Message----- From: Tony Duell <ard(a)p850ug1.demon.co.uk> To: Discussion re-collecting of classic computers <classiccmp(a)u.washington.edu> Date: Wednesday, October 20, 1999 5:47 PM Subject: Re: OT: how big would it be? >> >> > > Signetics 82mumble WOM (write only memory) april first version. >> > >> > Oh, she's good. She's very good. >> >> And old... >> >> Memory says 82s129, I have the data sheet home in that 1971 signetics >> data book. I was my first ttl databook! > >The 82S129 was a fusible-link PROM. It was an actual device, and in >production until quite recently. > >I have here the Signetics data sheet for the 25120 'Fully Encoded 9046*N >Random Access Write Only Memory'. I suspect that's the one you're >thinking of. It includes graphs of 'Bit Capacity .vs. temperature', 'Iff >.vs. Vff', 'Number of pins remaining .vs. Number of socket insertions' >and 'AQL .vs. Selling Price'... :-) > >Incidentally the nominal Vff is given as 6.3V. I wonder how many >modern-day engineers would realise the significance. > >If anyone wants to get this data sheet, it's reprinted on page 605 of the >'Student Manual for the Art of Electronics' by Thomas C Hayes and Paul >Horowitz (2nd Edition, ISBN 0-521-37709-9) > >-tony >

24 years, 9 months

OT: how big would it be?

by allisonp＠world.std.com

<Tristate didn't exist in the early days of TTL; the only way to do <busses was OC or with muxes. The way this affected the design of PDP-11 <CPUs is described at length in _Computer Engineering_. Actually it did at a premium cost. The other thing is it was a lousy bus driver. You had parts like 72125/6 and 8t97. The PDP-8E also reflected the open collector heritage and that fact also allowed some things like the ability to jam data to memory and "microcode" instructions. That and it was cheap. The offset was the absolute need for the bus loads module (terminated pullups). There was another benefit, a board that was not supposed to be selected and asserting a high (or not low) didnt fry the next board asserting a low. I encounted this for the first time on s100 (a dozen 8t97s vaporized) when a control signal failed and we had a bus jam. Allison

24 years, 9 months

Designs (was Re: OT: how big would it be?)

by CLASSICCMP＠trailing-edge.com

Eric wrote: >>Anyhow, the point is that if DEC copyrighted something in 1964, it >>IS still covered now, and the copyright belongs to Compaq unless it's >>been sold to someone else. To which I replied: >True, but in this case I think we're talking about copying the circuit, and >not the patent on the PCB artwork. And that's what is covered by a >patent, if anything. Oops! I got at least three things wrong in those two sentences. Let's try it again: True, but in this case we're talking about copying the circuit, and not about an exact copy of the PCB artwork. The artwork might be covered by a copyright, but the circuit is protected by a patent, and that's expired by now. -- Tim Shoppa Email: shoppa(a)trailing-edge.com Trailing Edge Technology WWW: http://www.trailing-edge.com/ 7328 Bradley Blvd Voice: 301-767-5917 Bethesda, MD, USA 20817 Fax: 301-767-5927

24 years, 9 months

Designs (was Re: OT: how big would it be?)

by CLASSICCMP＠trailing-edge.com

>Anyhow, the point is that if DEC copyrighted something in 1964, it >IS still covered now, and the copyright belongs to Compaq unless it's >been sold to someone else. True, but in this case I think we're talking about copying the circuit, and not the patent on the PCB artwork. And that's what is covered by a patent, if anything. -- Tim Shoppa Email: shoppa(a)trailing-edge.com Trailing Edge Technology WWW: http://www.trailing-edge.com/ 7328 Bradley Blvd Voice: 301-767-5917 Bethesda, MD, USA 20817 Fax: 301-767-5927

24 years, 9 months

8T26 buffers (was Re: Tandon TM 100 5 1/4" drives)

by edick＠idcomm.com

The National Semi DP8304 is a bidirectional bus buffer, but the 8T26 and 8T28 were only for a bidirectional bus on one side. The other side was separate in and out. They're not uncommon on S-100 boards. The DP8304 is bidirectional on both sides, like a '245. In fact it's exactly the same as the i8286. Dick -----Original Message----- From: Eric Smith <eric(a)brouhaha.com> To: Discussion re-collecting of classic computers <classiccmp(a)u.washington.edu> Date: Wednesday, October 20, 1999 4:46 PM Subject: 8T26 buffers (was Re: Tandon TM 100 5 1/4" drives) >> Not that I normally advocate this sort of cannibalism, but does not the >> Apple ][ use 8T26 bus buffers? They certainly are more common than OSI gear. > >No. Early Apple ][ used an octal bidirectional buffer whose exact part >number I've forgotten, but it was something like 8308. Later revs replaced >it with the 74LS245, which was not pin compatible. Some boards were >dual-patterned to accept either, although the socket was installed for >one, precluding the use of the other. > >8T26 chips are not that hard to find. I can probably supply some >if anyone needs them, although I'll charge a premium to cover my >handling costs.

24 years, 9 months

OT: how big would it be?

by allisonp＠world.std.com

<I've also been thinking about "cloning" a kinda 32bit clone of the <famous <TMS 9900. This chip had it's registers in memory and if such a design <would incorporate cache memory the results would still be respectable. <Especially if it could be done with programmable-asic technology. Doable and even without cache it can be fast as the moderm memory (under 10ns parts). Granted it doesnt take much to beat the old 9900 that clocked in at 4mhz for the "fast" parts and used 400ns memory. My favorite would be to do a stretch PDP-8, simple and could be very fast using FPGAs. Allison

24 years, 9 months

Designs (was Re: OT: how big would it be?)

by daniel＠internet.look.ca

-----Original Message----- From: CLASSICCMP(a)trailing-edge.com <CLASSICCMP(a)trailing-edge.com> To: Discussion re-collecting of classic computers <classiccmp(a)u.washington.edu> Date: Wednesday, October 20, 1999 2:14 PM Subject: RE: Designs (was Re: OT: how big would it be?) >>Ok, so who would be interested in creating a repository of "generic" gate >>designs? >> >>Are the flip chip cards copyrighted? (Somehow I doubt Compaq would come >>after us if we started building them :-) > >The PC artwork might be copyrighted, but the protection on the circuit >design would be a patent. And the patents have (in the case of >the "classic" technology being discussed) almost certainly expired >by now. > >>Are they the correct technology? I like 'em because you can get to parts of >>the circuit easily, but it is more compact to put everything on just a few >>boards. >> >>Have we ruled out using SMT technology? We could easily build a 16 bit >>register on a single flip chip sized card with SMT stuff. > >I, personally, don't think that surface mount is the way to go. I'd prefer >to see all the transistors in TO-3 cans, though of course real transistors >on flip chips often were TO-92's, and these offer a definite cost and >density advantage (as does SMT, but I think that's a bit too far!) The flip chips (R205 - Dual Flip Flop) used 61 diodes, 4 transistors, 24 resistors, and 8 capacitors. Most of the Flip Chips I have are pre '67 so they have the "round" transistors rather than the newer looking TO-92.I would not even want to build ONE of these! BTW: The modules were "Copryright 1964 DEC" so the patent is long gone. If anyone has a particular OLDER processor that would be interesting if converted to transistors then please email me (with any links to the CPU info if you have it). I do have quite a few analog flip chips so the processor *could* do something interesting. A SMT unit *might* be interesting... I can get all the PCBs done I want for free (must have some kind of standard blocks) but the SMT building might be difficult. Can the new pick and place machines handle TO-3s [not on tape]? I am sure I can find a surplus lot of a few thousand NPN/PNPs for pennies. If something can be put together here *collectively* (a LOT less parts than the usual Flip Chip board) I would be willing to buy some time on a Pick and Place around here and have it knocked out. john > >Tim. >

24 years, 9 months

OT: how big would it be?

by edick＠idcomm.com

These days, no one would seriously attempt to build a CPU equivalent using TTL SSI/MSI components simply because the packaging gets too much in the way of smooth data flow. I once built a 650x CPU equivalent on a 4"x6" wirewrap board using TTL SSI/MSI, but it was my goal to build one using the logic available to the original designers. That was not easy, but it fit only because of the efficiencies inherent in the 650x series timing and instruction set. If one were to do the same thing with an 8080 CPU design, I suspect it could be forced to fit on a board like an S-100 card. It might be difficult to do in "period" family logic, i.e. with the parts that were available to the designers of the 8080, though. If you'd like to convince yourself of this, take a look at the '72 TTL data book from T.I. or Signetics. If one were limited to 28-pin FPLD's and smaller, I think it could be done easily enough. That would take the emphasis off parts search and the occasional unavailability of some functions, while allowing some random logic to be localized in a single device rather than requiring several different flavors of AOI gates, expanders, etc. The internal data paths of the 8080 could more easily be done with today's tristate devices than back in '72-'74 with muxes of various types. There are FPGA cores, though . . . I personally think it would be fun to build an S-100 card to replace the 8080 LSI. It might well be possible to replace all the external support logic with the hardware that goes "inside" the device, and you could fiddle with the instruction set more or less like the folks with wire-wrapped PDP8 processors did from time to time. Dick -----Original Message----- From: Eric Smith <eric(a)brouhaha.com> To: Discussion re-collecting of classic computers <classiccmp(a)u.washington.edu> Date: Wednesday, October 20, 1999 12:25 AM Subject: Re: OT: how big would it be? >> Say someone were to home-build a CPU from scratch using only individual >> components, no ICs only modern descrete(?) components. How big would the >> CPU be? For comparison lets say it would be an 8080 clone. Any guesses? > >One of the vendors of bit-slice components (AMD 2900 or clone, I think) >offered a board that emulated an 8080. In addition to being faster than >an 8080, you could of course modify the microcode to add or change >instructions. IIRC, it looked like the board had about fifty chips. > >If you didn't use a bit-slice, you'd have to use separate ALU, memory, >and shifter chips, and you'd wind up with even more. > >The early microprocessor architectures were designed based on minimal >transistor count for a single-chip implementation. This does not result >in minimal chip count if you implement the equivalent in 7400-series >chips. It is quite possible to design useful processors with a lot fewer >TTL chips.

24 years, 9 months

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test-drb October 1999