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Thread: Calling All Hands - Yamaha C1 Laptop Expansion Slot

  1. #1

    Default Calling All Hands - Yamaha C1 Laptop Expansion Slot

    I've received a very interesting memo about the Yamaha C1 Music Computer.

    This machine had 8 MIDI slots and a special version of Sequencer Gold to use them all. Supplied with either 20MB MFM HDD and a floppy or two floppies.

    Needless to say the challenge is to get a CompactFlash storage board made for this machine. It has an expansion slot and that is specifically what I need help finding data on - physical dimensions, connector type and pin out, everything basically.

    All help on this greatly appreciated. This project is quite exciting because there is a real use case coming out of this

  2. #2
    Join Date
    Apr 2007
    Western United States


    Another BT adventure, I presume?

    Ethan O'Toole mentions having documented the expansion pinout on his blog. Might be worth reaching out to him for that information.

    Otherwise, you'll probably need to purchase the service manual.

  3. #3


    Awesome thanks for the links! I wonder how detailed the service manual is. A schematic would be perfect.

  4. #4
    Join Date
    Mar 2011
    Atlanta, GA, USA


    Quote Originally Posted by pearce_jj View Post
    Awesome thanks for the links! I wonder how detailed the service manual is. A schematic would be perfect.
    I bought the SM so it can be shipped quicker to a US address. They didn't offer expedited shipping. But anything would be quicker than to the UK.

    When it arrives, I'll scan it in and send it to you electronically. I can send it along in the post later if you want. I think I still have your mailing address here somewhere.

    Consider it a donation to 'the cause'.
    "Good engineers keep thick authoritative books on their shelf. Not for their own reference, but to throw at people who ask stupid questions; hoping a small fragment of knowledge will osmotically transfer with each cranial impact." - Me

  5. #5


    Thatís so super awesome, thank you! Scan would be brilliant

  6. #6


    With the very kind help of eeguru, the tech ref is now in hand

    Looks like the built-in HDD interface is *very nearly* IDE - everything we need electrically is there to interface to CompactFlash directly.

    The system ROM is apparently 64KB. I don't yet know if there is any free space in it or any available ROM sockets.

    Next step will be to look at these. The only challenge I think will be patching out the built-in HDD code and getting the XTIDE Universal BIOS stored somewhere and initialised.

  7. #7


    Here is the HDD Interface pinout:

    Screenshot 2019-01-05 at 20.49.48.jpg

  8. #8


    I've attached the system BIOS. Others have reported that Type 47 is not available in the interface but it is in the text list in the BIOS.

    We need to modify the BIOS by either:

    1. Adding XTIDE UB for generic 16-bit IDE controller at 1F0h in unused space (8K offset appears to be clear) and patching the BIOS to call it; or
    2. Patching the existing BIOS to enable type-47 selection.

    Any help on this greatly appreciated! Other than that a simple patch PCB to isolate unused signal wires (like motor run) is all that's needed on this
    Attached Files Attached Files

  9. #9


    James, I'm looking into patching XUB into the system BIOS but can't make any promises as to when or if it will be done. Just wanted you to know I'm giving it a shot.
    Looking for a cache card for the "ICL ErgoPRO C4/66d V"

  10. #10


    That would be so awesome Antilles, thank you!


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