Shop OBEX P1 Docs P2 Docs Learn Events
Simple Computer based on gates - Page 2 — Parallax Forums

Simple Computer based on gates

2»

Comments

  • I agree.
    The AM2901 was the basis for such systems as the IBM S/370 processors, and the DEC PDP-11 and DG Nova and Eclipse as well.

    In fact there are some of us who view such technologies rather fondly and use it (TTL) all the time.
    ----
    And why are all of your robots looking for a trip to Scandinavia, erco?
  • Cluso99Cluso99 Posts: 18,069
    edited 2016-09-17 00:03
    Dave,
    Very interesting. I recall looking at the bit-slice processors at the time. I used to pour over all the "really thick" data books put out by all the semiconductor manufacturers at the time. The Motorola ones were something like 11+ volumes IIRC. TI (Texas Instruments) put out an amazing 7400 book that had equivalent circuits and excellent descriptions.

    I cut my teeth on the Friden/Singer/ICL System Ten. IIRC it had 11 boards about 12-14" square loaded with TTL gates just for the CPU. All the TTL were custom labelled with 9? digits with no resemblance to the actual 74xxx chips. Of course internally we had a cross-reference table. Every computer came with a complete set of big schematic books. I used to repair the boards before we got an automated tester.

    Do any of you recall the first single chip micros - I mean complete with EPROM (the UV windowed types)? IIRC Intel had the 8751 and Motorola 68705P3S. I built a tiny board that had 2 x 68705P3S, 1x4011, 1x7404, 2x 2N4033 transistors (had to be Fairchild since they had poor frequency response) and a coil inside a large ferrite core. The 68705P3S had 1.8KB of EPROM and 112 bytes of RAM in a 28pin DIP. This replaced 3 large logic boards of TTL. The 68705P3S cost me $150 EACH for production - I was in production with pre-production chips because full production was delayed due to a clocking mode fault that did not affect me.
    At the end of my production I was paying <$8 per 68705P3S :)
  • I stumbled across my old 68705 emulator/programmer just last week.
    It was a locally made gadget (IIRC by Graham Blowes?) and served me well. :)
    528 x 296 - 73K
  • Heater.Heater. Posts: 21,230
    I arrived in the work place just at the time a lot of TTL based stuff was being replaced with micro-processors/micro-controllers.

    It was kind of dramatic. All of a sudden projects changed from being digital and electronic design to programming.

    When did the 8751 come out? Until recently I still had a box of them. Ceramic packages, gold plated pins and all. The company I worked for was paying something like 200 GBP a chip initially.


  • ozpropdevozpropdev Posts: 2,792
    edited 2016-09-17 04:44
    Found this link on a 8751 programmer published in 1990.
    https://www.elektormagazine.com/magazine/elektor-199011/32242

    Edit: Thinking about timelines I recall I was using a Intel 87C196KC 16 bit device in 1990 so 8751 must have been a lot earlier still.
  • Heater.Heater. Posts: 21,230
    The 8051 was developed in 1980. Not sure when the UV erasable 8751 arrived.
  • jmgjmg Posts: 15,173
    Heater. wrote: »
    When did the 8751 come out? Until recently I still had a box of them. Ceramic packages, gold plated pins and all. The company I worked for was paying something like 200 GBP a chip initially.

    Some history is found here.., for ROM, then EPROM in 3.5u HMOS (NMOS variant) then 1.5u CMOS
    http://www.cpushack.com/2016/04/28/the-evolution-of-the-intel-8051-processes/

  • Cluso99Cluso99 Posts: 18,069
    We recently moved. When I can access my filing cabinets my schematics will have a date on them. I expect the 68705P3S was sampling late 1981. At the time I was using MC6802. The 8751 was similar timing.

    By late 85 or early 86 we were using >70K 68705 yearly. I think at that time they were ~$20 each.
  • Heater.Heater. Posts: 21,230
    Seems like only yesterday that we nerds in my home town dispersed to various universities around the country. Then my friend wrote to me "Hey, have you checked out these new micro-processor things? We have been ordering them from the states..."

    That was 1976.

    I don't recall what micro he was talking about. Probably Motorola 6800.

    I recall discussing radar displays with my project manager in 1980. They were always looking at moving from vector graphics to raster displays. But he pointed out we would need 4096 by 4096 by 3 bytes of RAM to do what they want. That was crazy talk when the computers driving them only had 32 or 64K.

    How far we have come.

    Now I have 1GHz, 4-core, 32 bit, Raspberry Pi to play with.





  • The AMD2901/3 is still in use today in some avionic computers used by the Air Force.such as the B-52 B1-B and other bombers and fighters. Oh yeah they had core memory as well. IBM AP-101's to be precise. Even the old space shuttle used them.

    Internally they were something to behold. board after board of surfaced mounted TTL chips with chips on both sides of the board for glue and interface logic and dipped in a conformal coating for protection. IMS the boards were 12 layers.

    The later ones probably topped out at a 1/2 MIPS. Still more than enough to do the jobs they were meant to do which is quite impressive.

    The reason they're still in use is because they work and the costs of flight certification.


  • Yeah Heater nowadays the trick is accurately rendering classic vector games like Battlezone or Tempest on raster displays. It takes more computing power than existed in the entire world when those original games were in arcades.
  • jmgjmg Posts: 15,173
    Cluso99 wrote: »
    Do any of you recall the first single chip micros - I mean complete with EPROM (the UV windowed types)? IIRC Intel had the 8751 and Motorola 68705P3S.

    On the topic of longevity, the 8051 is undergoing something of a resurgence, and the 6805 has pretty much stalled at Freescale/NXP, with nothing new for a long time.
    Even the AVR is not looking too great, after the Microchip takeover, as prices trend up.

    Meanwhile, SiLabs, STC, Nuvoton, SyncMOS, ABOV (etc) all have new, highly spec'd 8051 variants.

  • kwinnkwinn Posts: 8,697
    Heater. wrote: »
    Seems like only yesterday that we nerds in my home town dispersed to various universities around the country. Then my friend wrote to me "Hey, have you checked out these new micro-processor things? We have been ordering them from the states..."

    That was 1976.

    I don't recall what micro he was talking about. Probably Motorola 6800.

    I recall discussing radar displays with my project manager in 1980. They were always looking at moving from vector graphics to raster displays. But he pointed out we would need 4096 by 4096 by 3 bytes of RAM to do what they want. That was crazy talk when the computers driving them only had 32 or 64K.

    How far we have come.

    Now I have 1GHz, 4-core, 32 bit, Raspberry Pi to play with.

    Speaking of radar displays, did you ever do anything with that CRT you posted about a while back?
  • Cluso99Cluso99 Posts: 18,069
    The 8080 slightly preceded the 6800 IIRC. But here in Oz Motorola was far better represented with FAE's.

    I bought one of the first batch of D1 kits and interfaced that into the System Ten mini. I bought one of the first batch of D2 kits into Oz too. Motorola had a little ~3" video monitor. A mate and I built that into a little terminal with keyboard. They were "fun" days. By day working on the mini, and by night doing all sorts of interfacing to the mini from the micro - blood analysers, printers, punches, etc, etc.

    I wrote my first cross-assembler for the 6800 on the mini. My first micro based board used a 6802, 6810 (128x8 RAM), 2716 (2Kx8 EPROM), 6820 (Parallel Interface Adapter = PIA). It interfaced a Centronics Printer into the micro.

    Certainly very exciting times and they were moving extremely fast for the day.

    When I finally get around to converting my 36mm slides onto my PC I should have some nice pics of the older days ;)
  • Cluso99Cluso99 Posts: 18,069
    Back to topic...

    I have moved on a bit and decided my first go might be using somewhat advanced 74LVCxxx chips such as...

    161's for the PC Counter as it permits loading and hence jumps

    573's for the latches (ACC, OUTA, etc). They can also be used as tristate buffers instead of 541's, and for INA.

    540 for the B inverter (for subtract in the ALU)

    74AC283's for the ALU (2x 4bit)

    74LS/HC688 possibly for the ACC=B ALU condition

    SRAM 32-512KBx8 ???

    P8X32A to decode the instruction set, provide the clock, and initialise part of the SRAM as ROM, and of course a serial interface.

    Haven't done much lately as currently more higher priority projects.
Sign In or Register to comment.