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FS: 8K S-100 LOGOS-I RAM Board

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  • Systems Glitch
    I m working on clearing out some of my extra S-100 boards. Here s a weird one: http://www.glitchwrks.com/4sale/logos-front.jpg It looks like a regular old 8K
    Message 1 of 5 , Nov 12, 2013
      I'm working on clearing out some of my extra S-100 boards. Here's a weird one:

      http://www.glitchwrks.com/4sale/logos-front.jpg

      It looks like a regular old 8K S-100 RAM board. Actually, it looks a lot like a clone of Processor Technology's 8K static RAM board. But wait, what's that in socket 76? Another 2102 SRAM?!

      I finally found a high-res picture of another one of these boards, and the 2102 is in fact in its correct location. I found that very odd when I received the board years ago, and avoided powering it up since I figured, "that can't possibly be right!" Seems to be, as I plugged the board into the IMSAI and found RAM starting at 0x1000. My theory, so far, is that the 2102 at location 76 is a sort of map RAM, allowing the 8K onboard to be scattered around through memory address space.

      The board has been tested as far as I'm able to. On power-up, it appears from 0x1000 to 0x43FF in my system. All of the RAM in this space tests fine with a 2 MHz 8080. The 2102s in the memory array are 400 nS so you shouldn't need wait states at 2 MHz. I can't find any documentation on it, other than a mention in an Advanced Computer Products 1978 catalog.

      E-mail me off-list if interested. Trades considered. In addition to offering the board for sale, I'd also be interested in any info relating to it!

      Thanks,
      Jonathan
    • Dan Roganti
      ... is pin 98 connected to that section on this board ? There was a new protocol on the ieee-696 Bus which can be used for Parity check. But since this board
      Message 2 of 5 , Nov 12, 2013




        On Tue, Nov 12, 2013 at 9:57 PM, Systems Glitch <systems.glitch@...> wrote:
        I'm working on clearing out some of my extra S-100 boards. Here's a weird one:

        http://www.glitchwrks.com/4sale/logos-front.jpg

        It looks like a regular old 8K S-100 RAM board. Actually, it looks a lot like a clone of Processor Technology's 8K static RAM board. But wait, what's that in socket 76? Another 2102 SRAM?!

        I finally found a high-res picture of another one of these boards, and the 2102 is in fact in its correct location. I found that very odd when I received the board years ago, and avoided powering it up since I figured, "that can't possibly be right!" Seems to be, as I plugged the board into the IMSAI and found RAM starting at 0x1000. My theory, so far, is that the 2102 at location 76 is a sort of map RAM, allowing the 8K onboard to be scattered around through memory address space.



        is pin 98 connected to that section on this board ?
        There was a new protocol on the ieee-696 Bus which can be used for Parity check. But since this board looks older, pre ieee-696, it's a stretch - but you know there were always derivatives of the S-100 bus well before the ieee-696 spec came out. Even though the extra 2101 is only 1Kx 1, it couldn't provide enough parity detection for the entire board. But there could be some other method being used in there. Too bad you can't find the schematics, but there isn't much there to pencil in the connections to see what's going on. I can't make out the connections from the traces in the pic of just the top. Not sure yet why it's only mapped to 0x1000. I would suspect there's some jumpers onboard (pcb pads) to make it configurable. I don't recall any S-100 memory boards being stuck to one mapping.

        Dan


      • Dan Roganti
        ... and it sounds like that has some addr mirroring problem stuck on that board. 8K = 0x1FFF you have an extra 0x1400 bytes :)
        Message 3 of 5 , Nov 12, 2013



          On Tue, Nov 12, 2013 at 9:57 PM, Systems Glitch <systems.glitch@...> wrote:


          The board has been tested as far as I'm able to. On power-up, it appears from 0x1000 to 0x43FF in my system. All of the RAM in this space tests fine with a 2 MHz 8080. 


          and it sounds like that has some addr mirroring problem stuck on that board. 8K = 0x1FFF
          you have an extra 0x1400 bytes :)


        • Dave McGuire
          ... That sounds very interesting indeed! One other thing it could possibly be is a software-controlled region write protect system. Man you ve gotta trace
          Message 4 of 5 , Nov 13, 2013
            On 11/12/2013 09:57 PM, Systems Glitch wrote:
            > I'm working on clearing out some of my extra S-100 boards. Here's a weird
            > one:
            >
            > http://www.glitchwrks.com/4sale/logos-front.jpg
            >
            > It looks like a regular old 8K S-100 RAM board. Actually, it looks a lot
            > like a clone of Processor Technology's 8K static RAM board. But wait,
            > what's that in socket 76? Another 2102 SRAM?!
            >
            > I finally found a high-res picture of another one of these boards, and the
            > 2102 is in fact in its correct location. I found that very odd when I
            > received the board years ago, and avoided powering it up since I figured,
            > "that can't possibly be right!" Seems to be, as I plugged the board into
            > the IMSAI and found RAM starting at 0x1000. My theory, so far, is that the
            > 2102 at location 76 is a sort of map RAM, allowing the 8K onboard to be
            > scattered around through memory address space.

            That sounds very interesting indeed!

            One other thing it could possibly be is a software-controlled region write
            protect system. Man you've gotta trace that out and draw a schematic!

            -Dave

            --
            Dave McGuire, AK4HZ
            New Kensington, PA
          • Systems Glitch
            ... I may have just figured out who made the board -- just got a 32K RAM board in to repair, made by S100 Computer Products. The design is very similar, and
            Message 5 of 5 , Nov 14, 2013
              > That sounds very interesting indeed!
              >
              > One other thing it could possibly be is a software-controlled region write
              > protect system. Man you've gotta trace that out and draw a schematic!

              I may have just figured out who made the board -- just got a 32K RAM board in to repair, made by "S100 Computer Products." The design is very similar, and the silkscreen font is almost identical to the font on the LOGOS-I board (reminds me of "Bellbottom Laser" TTF). Herb has a copy of the 32K manual as well as one for an 8K manual listed, so I'll probably order a copy and see how close it is!

              Thanks,
              Jonathan
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