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Thread: What is the Model 3 add-in board??

  1. Default What is the Model 3 add-in board??

    Odd board with a NEC 'processor on it, made by "Holmes" in 1982...

    Model-3_extra-board.jpg

    Ideas?

  2. Default

    Got it... It's a Holmes' Sprinter III speed-up board.

    Interesting, but kind of pointless in a vintage machine! (where you usually want "original" performance...)

  3. #3
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    Holmes sprinter III speed-up kit?

    I'd first have thought a CP/M mapper but i think it has too few chips to do that.
    *There is never a charge for Tech Support even if you don't purchase from me - We are Enthusiasts Helping Other Enthusiast and that is just the way it is

  4. #4
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    The NEC 780C-1 is the 4 MHz (Z80A) version of the Z80.

    Tom

  5. #5

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    Quote Originally Posted by AN7000_Dude View Post
    Got it... It's a Holmes' Sprinter III speed-up board.

    Interesting, but kind of pointless in a vintage machine! (where you usually want "original" performance...)
    Yeah on the Model I it was better because the LNW and a few others came with 4MHZ support. The Model 4 just does the Model III at 4 mhz if you do it right.

  6. #6
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    Apr 2015
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    Quote Originally Posted by Tibs View Post
    Yeah on the Model I it was better because the LNW and a few others came with 4MHZ support. The Model 4 just does the Model III at 4 mhz if you do it right.
    It's still of historical interest though. There was a whole lot of clever stuff done that was rendered obsolete/irrelevant soon after that's slipped through the cracks.

    As to "original" performance, I still want to see a reproduction XLR8er so I can build the 4D Tandy "should" have made

  7. #7

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    Quote Originally Posted by pjhacnau View Post
    It's still of historical interest though. There was a whole lot of clever stuff done that was rendered obsolete/irrelevant soon after that's slipped through the cracks.

    As to "original" performance, I still want to see a reproduction XLR8er so I can build the 4D Tandy "should" have made
    Yes, I want a reproduction XLR8er, too.

  8. #8
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    Jan 2014
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    Quote Originally Posted by Alphasite View Post
    Yes, I want a reproduction XLR8er, too.
    I've looked at this possibility before, and it shouldn't be too difficult to build an XLR8er 'workalike.' If you want a 'replica' with original DRAM's, 64-pin narrow-pitch DIP version of the HD64180, etc, that is made rather difficult by the lack of a sample to reverse-engineer. A workalike on the other hand can build from the specifications and use the PLCC68 version of the Z8S180. How close do you want it, in other words? (this should probably be a new thread, and I might start one later today.....).

    If you're wanting to build the 'Model 5' (not a typo), then that would be a whole new board, and I have some ideas about that, including using current production CPU's, either the Z8S180, the Z380, or the eZ80. Of all of those, the eZ80 would be the best, in my opinion, since my personal favorite, the Z280, has been out of production over 20 years. I have thought about a 'TRS-80 option board' to plug in to the CPU280, myself. But I just really like the Z280, that's all; the CPU280 design is not really amenable to memory-mapped peripherals on the ECB connector, so a daughterboard to plug in to the EPROM sockets would be the way to go.

    But that is definitely a different thread; sorry for hijacking this one. That Model III option board looked pretty neat!
    --
    Thus spake Tandy Xenix System III version 3.2: "Bughlt: Sckmud Shut her down Scotty, she's sucking mud again!"

  9. #9

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    Quote Originally Posted by lowen View Post
    I've looked at this possibility before, and it shouldn't be too difficult to build an XLR8er 'workalike.' If you want a 'replica' with original DRAM's, 64-pin narrow-pitch DIP version of the HD64180, etc, that is made rather difficult by the lack of a sample to reverse-engineer. A workalike on the other hand can build from the specifications and use the PLCC68 version of the Z8S180. How close do you want it, in other words? (this should probably be a new thread, and I might start one later today.....).

    If you're wanting to build the 'Model 5' (not a typo), then that would be a whole new board, and I have some ideas about that, including using current production CPU's, either the Z8S180, the Z380, or the eZ80. Of all of those, the eZ80 would be the best, in my opinion, since my personal favorite, the Z280, has been out of production over 20 years. I have thought about a 'TRS-80 option board' to plug in to the CPU280, myself. But I just really like the Z280, that's all; the CPU280 design is not really amenable to memory-mapped peripherals on the ECB connector, so a daughterboard to plug in to the EPROM sockets would be the way to go.

    But that is definitely a different thread; sorry for hijacking this one. That Model III option board looked pretty neat!
    I'll wait for you to start that thread as I am definitely interested.

  10. #10

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    Quote Originally Posted by Alphasite View Post
    I'll wait for you to start that thread as I am definitely interested.
    There are schematics and instructions for a clone of one, I have them on floppy somewhere around here. Its ASCII drawings so lots of fun. Whoever made it was pissed about MISOSYS not releasing schematics, at least I think thats why they did it. I started to look at it and got distracted with a Model 16a.

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