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Thread: Cloning apple iie card?

  1. #1

    Default Cloning apple iie card?

    I recently got a Mac performa 550 and know that the PDS slot is compatible with the iie card, I looked on eBay to see if I could find one and was surprised to see that the lowest priced one was $400!! That got me thinking Iíve seen people make with an FPGA a whole apple ii so Itís gotta be possible to make a ii card with some modification to the code. How would some go about cloning a iie card with an fpga would the trouble be worth it, is it something anyone else has thought of doing this? I know I wouldnít be able to with my current knowledge of Programming most I know is basic and a bit of Java. I think the biggest hurdle would be to find a donor slot from a broken pds card and wiring it up.

  2. #2
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    Cloning the IIe card is going to cost you a whole lot more than $400. You'd spend less money getting an actual IIe and have better compatibility. The IIe card uses a 65C02, the later CMOS variant which was not 100% backwards compatible with the HMOS 6502, which was used in older IIe machines. Software which relied on undocumented instructions (illegal opcodes) will not run on a IIe card or the later IIe models with a 65C02 CPU.

    To be able to reverse engineer the IIe card and make a clone that would be 100% compatible with the original would be a monumental effort that would likely cost at least several thousand dollars in man hours and more in prototypes and parts. You'd need extensive knowledge of digital electronics, assembly programming and be intimately familiar with two completely different computer platforms at the hardware and firmware level.

    The PDS connector is the least of your concern, you can still buy them today since many computer systems used them for bus connections.

    https://www.newark.com/harting/09-73...N41612%2096way

  3. #3

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    I believe there are already open source FPGA implementations of the 6502 that are near 100%

  4. #4

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    Yep. Get your hands on that and it shouldn't be too difficult.

    I've only seen NMOS 6502 reimplementations, but that doesn't mean that there aren't WDC or Rockwell 65C02 reimplementations by now.

  5. #5
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    You can still buy 65C02 parts, there's no real need to emulate it in FPGA.

    What will need to be implemented in FPGA is the Mega II chip, which is basically an entire IIe sans ROM, RAM and the CPU.

    The reason nobody has cloned this card is because it doesn't really make sense. Why clone a card for an old machine designed to emulate an even older hardware system when you can just emulate it in software on a modern machine or something portable like a raspberry pi?

  6. #6

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    That makes a lot of sense I only posted as a thought exercise and to see what others with more experience thought of the idea. I didn’t even think about the integrated woz chip, I know I could easily emulate an apple iie or I could just use the ii plus I already have, but where’s the fun in that haha . Thank you

  7. #7
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    I don't remember if the IIe card has a discrete IWM chip, or if it's integrated into the Mega II chip. There have been various projects to emulate the IWM in CPLD+ROM and FPGA, but I don't think a full 100% compatible implementation was ever done.

  8. #8

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    Discrete. I blew one by carelessly plugging/unplugging disk drives while the machine was on.

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