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Thread: Poly 88 case

  1. #21
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    Thanks guys.

    I'd love to try making a DG640.. but have not been able to find any artwork. The microbee forum is really difficult to get through because it is tightly restricted due to legal issues. They have some sort of rain dance you have to do to grt access to the archive with the ROMs etc.

  2. #22

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    The video board has a connector that can go to a parallel keyboard. The video was one of the first to have some form of block graphics so are reasonably easy to come by, compared to the CPU card.
    The CPU card had 512 bytes of SRAM. Not a lot but usually enough for the stack and monitor operations. The monitor ROM fit in one 2708. This gave quite a bit of information on the video output. The monitor was packed into the 2708 and didn't have enough memory for the cassette write. One of the first things a person would do is to enter the SMD code to dump a program to the cassette and saved it. It resided in that small space on the CPU card. There was also a cassette based asesmbler, 8K BASIC and a 12K BASIC. There were a number of cassette based games as well. It also has a single step but as I recall the code had to be in RAM. There were 2 more sockets on the CPU card for 2708s. These could be used for a version of PaloAlto Tiny BASIC. The binary code for this Tiny BASIC is available on the web. Normally, main system RAM needed to start at 2000H. There was a simple modification needed to handle DRAM boards but there was no issue with static RAM. The CPU board had a USART that could be used for cassette or serial to terminal/printer. These two functions required and additional board at the connector. The serial board was mostly just the level converters for TTL to RS232. The cassette board was a little more complicated and has at least one chip that would be hard to find. The keyboard also sometimes had a small board at the connector for the keyboard but this was usually only to take the ribbon cable to the 25 pin D. It some times had a zener or regulator to create the negative voltage for those keyboards that needed a negative voltage. The older video boards had circuitry to put a resistor and zener. Newer video boards needed the external board if a negative level was needed.
    The Tiny BASIC was intended to be able to have instructions added to it. I added a PEEK, POKE and a SAVE instruction that I'd load from cassette. A programmed saved this way would auto load and leave one at the TB prompt to RUN or edit. I could have made it auto run the program but felt it was more useful this way. To run only needed a R. to start.
    If one can find them, one could upgrade the Poly88 to a System88 but one needed to get the floppy disk card and a disk drive.
    Sometimes empty chassis would be bought to expand the bus with a couple of 100 pin connectors or a single one if soldered to one of the chassis.
    The one major problem with the Poly88 was lack of cooling. This is why chassis are often found without the orange cover.
    Should you ever get enough to make the cassette work and have a serial card, I have a small bootstrap program that you can use images of the cassettes to bring up any of the cassettes that we've recovered.
    Dwight

  3. #23
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    Thanks Dwight. I believe my Poly case still has the cassette board.. I found a picture that purports to be one.. it's a rather small board with a DB25 at one end and 7 or 8 ICs. Quite compact?

  4. #24

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    Hi
    Then you need to find a CPU card. That is a more serious issue. There are just not that many, not in a System88 or Poly88 already. It was not a convenient board to do CP/M with so not as likely to be bought for that purpose. I've seen a CPU card on ebay once but it will be a tough one to come on.
    Making a serial board is not too complicated.
    Dwight

  5. #25

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    Advanced Digital manufactured a couple of integrated single board S-100 Systems. The more well known processor board was the Super Single Six, which contained a 6mhz Z-80A processor. The Advanced Digital boards had processor, floppy controller, I/O ports, and system memory on them. There was even a design that had a hard disk controller on it.

    They sold CPM-80 preconfigured for the system so there was no hassle trying to get the OS customized to work with the board.

    Advanced Digital Boards show up on eBay occasionally for less than $300. The other choice is the JAIR8080.

  6. #26
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    I just scored two Poly 88 cpu cards and 1 video terminal card! For $195!

    That brings my total investment to $395 including my case. Not bad since I've seen these things go for $800+.

    Who knows if the cards work though..

  7. #27
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    Doing pretty good there! Let me know if you're interested in parting with one of the CPU cards. If you have trouble getting them going, I'm happy to go through them for you.

  8. #28

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    You're on your way. The serial card can be made with as little as a tristate buffer and one of the maxim rs232 chips ( and possible inverter chip for glue logic ). There is a bit that comes from the CPU card that selects which card the USART listens to, either the serial card or the cassette card ( in case your wondering what the tristate buffer is for ).
    Dwight

  9. #29
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    Will most any S100 serial board work? I see lots out there.. PT, Morrow, etc.

    Glitch - sure -- perhaps we could do a trade? I believe you have that 480 board I'm looking for to properly complete my 500 'Superkit' setup. If interested.

  10. #30
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    Quote Originally Posted by falter View Post
    Will most any S100 serial board work? I see lots out there.. PT, Morrow, etc.
    Dwight is referring to the little daughterboard for the Poly-88's CPU card serial port, which selects between cassette and the actual serial port. You can also use other S-100 serial boards in the Poly-88, though they make take some reconfiguring. A lot of S-100 stuff can be persuaded to work together, it just takes some effort sometimes. As long as you're not trying to do something totally mismatched, like trying to use a 16-bit only board in an 8-bit system.

    Quote Originally Posted by falter View Post
    Glitch - sure -- perhaps we could do a trade? I believe you have that 480 board I'm looking for to properly complete my 500 'Superkit' setup. If interested.
    Yep, I've still got it. I'll send you a PM.

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