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| Macintosh IIcx custom ROM |
Posted by: luRaichu on 2026-05-20 10:41:28
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 |
Posted by: frontein1 on 2026-05-21 21:29:44
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) |
Posted by: Bolle on 2026-05-22 02:08:33
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. |
Posted by: Joopmac on 2026-05-22 03:05:43
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 |
Posted by: luRaichu on 2026-05-22 06:59:20
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? |
Posted by: croissantking on 2026-05-22 07:27:05
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. |
Posted by: joevt on 2026-05-22 14:42:34
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). |
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