> 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.
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.
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