Macintosh SE/30 ROM Modifications

[jmacz]

Sorry, third thread on this (one for each of the IIfx, IIci, and now SE/30).

Again, most people will opt for the Rominator or similar custom ROM. But a few folks were looking for a stock SE/30 ROM but with the memory test disabled (and stock checksum preserved) in order to boot faster and allow the ROM to be identified as an SE/30 by 3rd party products. Again, posting this as a reference for anyone interested.

; Disable the checksum check. Could have changed the checksum
; but decided to leave it in case anything reads the checksum
; and is expecting the stock value. Change:

00002ab0 : 4efa 0c3a
00002ab4 : 4a86
00002ab6 : 6600 0184

; to be:

00002ab0 : 4e71
00002ab2 : 4e71
00002ab4 : 4e71
00002ab6 : 4e71
00002ab8 : 4e71

; Disable the memory tests. Change:

0000373a : 4cfa
000037e6 : 4cfa

; to be:

0000373a : 4ed6
000037e6 : 4ed6

; If you want to change the happy mac icon on boot, the icon is at:

00001948 : 128 bytes (32 x 32 bits)

; and the mask is at:

000019C8 : 128 bytes (32 x 32 bits)

 

[jmacz]

Attached the stock SE/30 ROM with the above modifications. I haven't tested it thoroughly but it was working on my SE/30 and bypassing the memory checks, and also not complaining even though the checksum was left stock.

 

[GerrySch]

Does this include upgrading the ROM code to 32-bit clean? If yes, then I don't have to edit my BlueSCSI disk images to boot properly on my SE/30?

Thanks for doing this,
Gerry

 

[Bolle]

Thank you @jmacz
That’s really useful.

Does this include upgrading the ROM code to 32-bit clean?

No.

 

[croissantking]

@jmacz I often run my stock ROM with Mode32, which tests the RAM after the first soft reboot.

Does this mod disable Mode32’s check as well?

 

[jmacz]

@jmacz I often run my stock ROM with Mode32, which tests the RAM after the first soft reboot.

Does this mod disable Mode32’s check as well?

Yes, the modified rom provided earlier does work with mode32 and skips the memory check. Looks like mode32 is triggering the stock check so the patches still work.

 

[croissantking]

Yes, the modified rom provided earlier does work with mode32 and skips the memory check. Looks like mode32 is triggering the stock check so the patches still work.

I suspected that. Very cool stuff.

 

[Belka2]

Again, most people will opt for the Rominator or similar custom ROM. But a few folks were looking for a stock SE/30 ROM but with the memory test disabled (and stock checksum preserved) in order to boot faster and allow the ROM to be identified as an SE/30 by 3rd party products. Again, posting this as a reference for anyone interested.

Very cool stuff.

I have a Rominator, but I went back to the original SE/30 ROM, because I can't use floppy disks with the accelerator.
Is it possible to modify the ROM image on the original SE/30 SIMM?
My SE/30 would then have the original parts (except capacitors and wires)

 

[croissantking]

I have a Rominator, but I went back to the original SE/30 ROM, because I can't use floppy disks with the accelerator.
Is it possible to modify the ROM image on the original SE/30 SIMM?
My SE/30 would then have the original parts (except capacitors and wires)

Nope

 

[Belka2]

Nope

I will order new ROMs with 4 chips, they look similar .