The Mac Plus Kanji ROM

[AndyDiags]

I have a Japanese Mac Plus with a "Kanji" sticker on the ROM.

I checked the part number, and indeed it's a different part number than the standard ROMs in the rest of the world.

ROM Rev	ROM-HI Part #	ROM-LO Part #
V1	342-0341-A	342-0342-A
V2	342-0341-B	342-0342-A
V3	342-0341-C	342-0342-B
Japan Kanji ROM	342-0441-A	342-0442-A

Since the part number was higher, I was wondering if the Japan Kanji ROM is newer then the V3 ROM, with some possible additional fixes.

Online search only found this website where a person discusses issues with external SCSI hard drives, and mentions that the Japan ROM is based off the V2 ROM as it doesn't contain SCSI fixes in V3. This was unfortunate.

I dumped the ROM to compare and see the different, and actually the Japan ROM and V2 are exactly the same! Contents of 342-0441-A is same as 342-0341-B, and contents of 342-0442-A is same as 342-0342-A! This doesn't make much sense to me. Why would Japan region have a different part number even though the contents were the same! Checking back to the previous website, I did notice that on a different page he did mention the Japan ROM and V2 was exactly the same. So indeed, there are only 3 known Mac Plus ROMs.

PS, that second link has a pretty cool article on how to convert an ADB mouse to Serial. Theres also a lot of other interesting information on the site, but all in Japanese.

 

[jajan547]

Mind sharing the ROM? My guess is it's the same ROM with minor changes I've seen a few on Buyee while not this exact type, they are some for companies like Kodak and such. Could also be a region thing as well.

 

[AndyDiags]

No need to post rom as no minor changes exist. they have the same 4D1EEAE1 checksum. I pulled the Old World Mac ROMs Mac Plus V2 ROM. split it into two files w/ low and high byte, and then ran a file compare with those against the ones I dumped. Bit for bit identical.

Here is the final table, as the V2 goes by two different part names:

Mac Plus ROM Rev	ROM-HI Part #	ROM-LO Part #
V1	342-0341-A	342-0342-A
V2	342-0341-B 342-0441-A	342-0342-A 342-0442-A
V3	342-0341-C	342-0342-B

As mentioned in the linked article, if you ever plan on using a real external 3rd party hard drive (non Quantum/Seagate) such as a IBM or Fujitsu, and you have the V2 ROM, make sure the hard drive supports enabling the "Unit Attention" function. If it doesn't, you'll need to update your ROM from V2 to V3 in order to boot from the external hard drive.