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Thread: Cheap homebrew ISA->PC104 adapters

  1. #1

    Default Cheap homebrew ISA->PC104 adapters

    I've been playing with PC104 CPU boards recently and was frustrated by how expensive it is to plug an ISA card into them. Most adapters are more than $100 and that seems ridiculous when you could probably make your own DIY adapter reasonably easily using IDC connectors and ribbon cable.

    But I was doing a big PCB order anyway so decided to spend a couple hours knocking up some boards, cost each less than $20 :




    The small one leaves access to the main board but means that the card lies outside the PC104 footprint :




    The large one sort of folds the ISA card back on top of the PC104 board and is probably more useful if putting the assembly in an enclosure :




    I tested them and they work great! Here's a video of my old Ensoniq Soundscape Opus running on an Advantech PCM-5890 :




    Gerbers for the boards can be found here (your fab house will need to be able to do 5mil trace/space) : http://rasteri.com/ISA_PC104_Adapter_Gerbers.zip

    And the source CAD files are in Altium Circuitmaker's cloud : https://circuitmaker.com/Projects/De...-PC104-adapter

    This is just the first revision so don't go plugging anything irreplacable into it until I've done more testing, but they seem to work perfectly for me on all the cards and motherboards I've tried. There's no decoupling capacitors or anything since I figure most ISA cards will have plenty on board, and the traces aren't very long anyway. The power traces are thicker than the data traces but they could perhaps be even thicker, I don't know how much current an ISA slot is expected to cope with.

    The designs are public domain, do with them as you wish.

  2. #2

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    ooh, this is quite interesting
    I've got an ISA SBC that works great, but the onboard video chipset is dead, so I have to use an external vga card. This will be of great help, if I ever get around to doing anything with that.
    Current favorites: IBM 5160 (EGA+Hercules+PGC, 8 floppy drives, XT-IDE), DCC D-116 (Nova 1200 clone), ASR 33 Teletype (now FULLY armed and operational! Mostly.)
    Wishlist: IBM 5161 (expansion chassis), Diablo 31/RK02/RK05 or equivalent, Data General Nova software, and the meaning of life.

  3. #3

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    Well Done!

    I've got some of those expensive ISA/PC104 conversion boards- bought 20+ years ago. These look good.

    Have you considered selling them?

    I've been updating the PC104 CPU boards on some of my older systems, bought the ICOP VortexDX3 based PC104 boards- at $70 each. So far, they are running DOS, Pharlap DOS, Win98, and Win XP.

  4. #4

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    Quote Originally Posted by BrianS View Post
    Have you considered selling them?
    Hmmm.... I don't really have the time to manually assemble very many and I don't think there would be enough demand to do a proper production run (would need to be in triple digit quantities to make it worthwhile really).

    If anyone deperately wants one though get in touch, I do have half-a-dozen unpopulated boards that I could be persuaded to assemble for maybe $40 each.

  5. #5

    Default

    Quote Originally Posted by BrianS View Post
    Have you considered selling them?
    Interesting idea but I don't think there'd be enough demand to do a proper production run, and I don't have time to manually assemble them.

    That said though if anyone wants one get in touch, I could maybe be persuaded to build a few.

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