View Full Version : Macintosh II ROM hack; custom boot chime & icons

September 27th, 2011, 09:31 AM
I thought a lot of you might appreciate the hack that's currently developing over at 68k MLA:


User dougg3 started by poking and decoding the ROM on a Macintosh IIci, and eventually figured out how the startup chime and icons are stored. He successfully modified the ROMs and created a custom boot chime and boot icons for his IIci. Check them out:

Super Mario Bros. boot chime:

Macintosh Performa boot chime on a IIci:

Mac IIci with custom boot icon (Apple Logo):

This project has now evolved into a ROM SIMM that can be used in all Macintosh II models with a ROM SIMM slot, including the SE/30. They have socketed flashable ROMs so you can make modifications on the fly, then just stick the SIMM in the slot and pull the jumper! :)

Being a liberal arts major I couldn't help much with the technical bits, but I did design a customized Jolly Roger for the project. Revision 1 of the boards are working on all Macintosh II models (including SE/30) except for the IIsi, which requires a minor modification. Revision 2 of the boards will work with the IIsi without any mods, and will include the new Jolly Roger logo. Possibly with red LEDs in the eyes! :D



From what I understand, the ROMs are bigger than the original, so it has more space to allow for all sorts of hackable possibilities.

September 27th, 2011, 10:17 AM
Very cool! Like the crossed pistols jolly roger. What stage is this project in? Are the custom ROM simms available?

September 27th, 2011, 10:27 AM
That is fantastic! Love the Mario boot chime. I have a IIsi here ready and waiting for a revision 2 :)

September 27th, 2011, 10:43 AM
Super cool. I'll have to get one and see if I can't drop the original Mac boot chime in place, I never cared for the Mac II boot chime.

September 27th, 2011, 11:06 AM
Those ROM SIMMs better be available in 32-bit clean form. SE/30 owners were always after them to run a hacked copy of MacOS 8.1 on their machines.

September 27th, 2011, 11:12 AM
32-bit clean is a software question, not a hardware one, so as long as you've got a 32-bit clean ROM image to put on it it should be fine.

September 27th, 2011, 11:47 AM
What commodorejohn said. For legal reasons, he can't sell them with the ROMs. No one can sell a Mac ROM. The SIMM itself is physically compatible with any Mac II (including the SE/30) with a ROM SIMM slot (i.e. II, IIx, IIfx, IIci, IIcx, IIsi, SE/30.) You can flash a 32-bit clean ROM onto it from a compatible Mac that you own. I believe there are one or two utilities for extracting the ROM from your Mac.

The current state of the project is a fully developed, working revision 1 board. It is unpopulated, so you have to solder the resistors and ROM sockets yourself. I believe he's selling the Revision 1 boards and will be starting the Revision 2 boards. The main difference is that the Rev 2 board will work on a IIsi without any modification to the SIMM. It should also include the Jolly Roger. :) May or may not include the glowing red eyes. ;)

October 18th, 2011, 01:44 PM
Revision 2 of the ROM SIMM has been released from the manufacturer and will be assembled soon. This new one includes the Jolly Roger I designed with 2 red LEDs for eyes. :D

It's also been updated to be useable on a IIsi with no modifications.

As a side note, the thread has also opened up discussion on designing a USB board for programming the SIMM; and not just the Mac II SIMM, but other computers as well such as the 6100, Network Server, 9600, and the 9700 prototype (which is difficult to use because of the scarcity of a clean ROM.)

October 27th, 2011, 09:03 AM
Revision 2 ROM SIMM has been received. :D


Check out the pics! Totally awesome.

October 31st, 2011, 08:51 AM
It's aliiiiive! :D


November 11th, 2011, 10:46 AM
A IIci with my custom SIMM! All thanks to dougg3 at 68k MLA.


You can order a fully assembled board for $29 (price includes shipping.) He also has perfectly good Rev 1 boards as well as sells just the board by itself so you can assemble it yourself.

These are the icons I used:


The boot chime is the Arrr! from Pirates! Gold. :D