Macintosh IIcx custom ROM

[luRaichu]

Hi,
I'm looking for a IIcx compatible ROM that only has the memory test disabled and is 32-bit clean. The examples I've found include a ROM disk which I don't want or care for. Thanks

 

[frontein1]

My IIcx is down for the count right now. But you can drop a IIsi ROM in the IIcx. This would give you a 32-bit clean ROM.

So really you probably want a IIsi ROM with just the memory test disabled (and vicariously the ROM checksum altered to not fail) right? If so give the attached a run (assuming you have a SIMM and a programmer handy)

 

[Bolle]

This will do: https://68kmla.org/bb/threads/macintosh-se-30-rom-modifications.49789/
IIcx and SE/30 have identical ROMs.

Edit: a scratch that, I missed you were looking for 32-bit "clean" ROMs.

 

[Joopmac]

I know of and use this one http://synack.net/~bbraun/macsrc/iisi+romdrv0.9+nomem+nosum.bin
IIsi 32-bit clean; No ROM disk, and no RAM test
see http://synack.net/~bbraun/macromboot.html

 

[luRaichu]

So really you probably want a IIsi ROM with just the memory test disabled (and vicariously the ROM checksum altered to not fail) right? If so give the attached a run (assuming you have a SIMM and a programmer handy)

Why is it double the size of a IIcx ROM?

 

[croissantking]

Why is it double the size of a IIcx ROM?

The IIcx ROM was older generation, whereas the IIsi was a newer universal ROM, so it was expanded.
Apple doubled the size of the ROM several times between 1986 and 1998, eventually ending up with 4MB ROMs.

 

[joevt]

Apple doubled the size of the ROM several times between 1986 and 1998, eventually ending up with 4MB ROMs.

68K Macs stopped at 2 MiB.

The first 1MiB ROM is probably this one:

067c.15f1    1991-10 - 420DBFF3 - Quadra 700 & 900 & PowerBook 140 & 170

These are the 2MiB ROMs:

067c.30f1    1994-05 - B6909089 - PowerBook 520 520c 540 540c
067c.30f2              B57687A5 - PowerBook 550c
077d.10f3.1  1994-09 - 5BF10FD1 - Quadra 660av & 840av
077d.2bf1.6  1995-08 - 4D27039C - Powerbook 190 & 190cs

Power Macs switched to 4 MiB to add all the PowerPC stuff.
3 MiB for the 68K part (includes PowerPC stuff that runs in MacOS).
1 MiB for the PowerPC part (ExceptionTable/Startup, HWInit, Nanokernel, 68K emulator, and Open Firmware for PCI Macs).