from Hacker News

The Lost Japanese ROM of the Macintosh Plus

by ecliptik on 5/17/25, 11:12 PM with 45 comments

  • by wolfgang42 on 5/18/25, 4:58 AM

    > Mini vMac is better suited for this, but it checks the ROM’s checksum, so I couldn’t boot with mine—it’s not in the recognized list.

    You can compile Mini vMac without checksum verification (either yourself or with the variations service[1]), which will allow you to use unknown or completely custom ROMs, though you need to be aware that it patches the ROM (it doesn’t emulate the original floppy hardware; instead it pokes a custom driver in where the original one ought to be) so if your ROM doesn’t line up with the original you will have problems with random chunks being overwritten.

    I’ve done this so I could use Mini vMac to learn assembly language: the Mac has the convenient property that pixels on the CRT are 1:1 the contents of a chunk of RAM at a fixed offset, so you can get very immediate visual feedback about what your program is doing. I just set up an assembler to dump raw machine code and named it "Mac128K.ROM" and Mini vMac picked up on it fine.

    [1] https://www.gryphel.com/c/minivmac/var_serv.html - though since Paul Pratt disappeared a few years ago nobody is quite sure how the server is staying up

  • by hoherd on 5/17/25, 11:28 PM

    Coincidentally I had never heard of KanjiTalk until earlier this week when I stumbled across it on infinite mac.

    https://infinitemac.org/1996/KanjiTalk%207.5.3

  • by nxobject on 5/18/25, 3:12 AM

    For what it’s worth, this wasn’t the first Japanese-localized Mac with Kanji fonts - Canon modified a 512k Mac by adding an extra ROM board and called ugh the Dynamac.

    http://g00nejp.fc2web.com/Macintosh_CM/index.html

  • by innocentoldguy on 5/18/25, 5:26 AM

    I found an old, unopened Apple box containing a Japanese Apple II Plus while cleaning out my in-laws house last month. I also found a fake-leather carrying case for it (also unopened). Both are from 1979.

    It was interesting to discover that the Apple II Plus' ROM didn't support Kanji, but there were third-party add-on cards that added Kanji support. The Apple II Plus I found had a Multitech Kanji Card with it. Multitech later became Acer.

  • by zdw on 5/18/25, 3:17 AM

    There's also a 1MB EEPROM mod you can do on a Mac Plus that gives you a built-in ramdisk: https://www.bigmessowires.com/mac-rom-inator/

    I wonder if one could put this larger ROM, and the other files into a custom built image so no swaps are required.

  • by ChilledTonic on 5/17/25, 11:34 PM

    The fact that this was machine translated was surprising as it was remarkably readable! Interesting how far that tech has come while I wasn’t looking.