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Thread: Calling All Hands - Yamaha C1 Laptop Expansion Slot

  1. #11


    Autocorrect LOL

  2. #12


    I've disassembled the system BIOS completely and found more than enough free space, so any build of XUB can be patched in. My plan is to patch it in at offset 4000h. The option ROM scan stops at segment F000h so I will have to extend that, then adjust the checksum and it should be good to go. I'm thinking that the Large AT build should be OK to use? I will also configure it to use a single standard 16-bit ISA IDE controller at 1F0h, not using any IRQ (for max performance).

    Does this sound OK?
    Looking for a cache card for the "ICL ErgoPRO C4/66d V"

  3. #13


    All spot on.

    If you can pull this off that will be super amazing!

  4. #14


    Can you see the built in code scanning 1F0h btw? Ideally we’d patch that out or perhaps we don’t need to?

  5. #15


    Quote Originally Posted by pearce_jj View Post
    Can you see the built in code scanning 1F0h btw? Ideally we’d patch that out or perhaps we don’t need to?
    We shouldn't need to do that. I'm assuming that the system BIOS can be configured to have no harddrives? Do you have access to this machine for testing, BTW?

    Anyway, I've patched in the Large AT build of XUB r600+* beginning at offset 4000h and ending at offset 67FFh. At offset 6800h I've changed the byte there from FFh to F9h to offset the change I did when extending the option ROM scan to segment F600h. The thing is, I can't find any code that checks for a valid checksum of the system BIOS so this might not be needed. The change I did to extend the option ROM scan is at offset 8D8Eh.

    I've attached a zip file with;
    the IDA database file containing the disassembly,
    BEFORE.BIN which is the first part of the original binary up to offset 3FFFh,
    FF.BIN which is just the part of the original system BIOS that is replaced by XUB,
    the XUB binary configured as I said above
    and AFTER.BIN that is the part that comes after XUB.

    Note that I have not patched AFTER.BIN to include the option ROM scan extension or the checksum byte so you can do
    to get a copy of the original BIOS in SYSTEM.BIN.

    The included C1ROMXUB.BIN is the complete BIOS patched and ready to go (I hope)!

    The zip file had to be split into two parts so I could attach it to this post, just do a
    copy/b C1ROMXUB.ZIP

    * r600+ meaning some small changes I've done that will be added to the repository on my next commit.
    Looking for a cache card for the "ICL ErgoPRO C4/66d V"

  6. #16


    Krille, thank you so much, this is literally ridiculously cool.

  7. #17


    PCB layout is done, just awaiting confirmation of sizing and mounting hole placement.

    Anyone with a C1 interested to test? This solution replaces the factory RLL HDD and controller with a standard 16-bit IDE controller for use with any IDE disk or CompactFlash card, powered by the XTIDE Universal BIOS patched in to the system ROM.



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