After reading what
@dougg3 wrote, I went back through my old emails from August 2023 (when I made my ROM SIMM video), and found that I did test what Doug suggests...
I used the Kero's Mac Mods "Crucible" app to create a bootable System 6.0.7 DSK image, then I used the app to generate the 4 files. I programmed the 4 files to individual chips on Kay Koba's 2MB ROM SIMM using the v2 SIMM Programmer app, then tested on my SE/30 by pressing "r" and "a" keys held down. It boots as a RAM disk
In other words, you can use Crucible like normal, choosing your custom icon, then export the 4 files from Crucible, then use Doug’s app to flash those 4 files to the individual ROM chips, just as Doug said. It's really neat because you just leave the chips socketed in the ROM SIMM (sitting in your v1 ROMmate programmer), and then Doug's app will write the 4 separate files to the chips. In fact, I found another old email which contained my video notes as follows...
For 2MB ROM SIMM from Kero's Mac Mods:
- In the top right corner of the ROM SIMM Programmer app window, click the "SIMM Capacity" popup and choose "2MB (4x 4Mb PLCC)".
- At the bottom left of the ROM SIMM Programmer window, click the "Flash individual chips..." button.
- You will see two groups of 4 checkboxes each. Put a checkmark in the top 4 checkboxes because you want to FLASH (not READ).
- Click the "Select file..." button to the far right of "Flash IC1" and choose the "U1.bin" file you previously created with Crucible.
- Repeat Step-3 for U2, U3 & U4.
- Click the "Flash chip(s)" button. The green LED will flash rapidly on the Programmer, and a progress bar will appear on your computer. Please wait until you get a confirmation programming is complete.
- Switch OFF the Programmer.
- Remove the ROM SIMM.
- With your vintage Mac powered OFF, insert the ROM SIMM carefully.
- Power-on your vintage Mac, and press the "R" key to boot from the ROM. (If you did not use Crucible to create your files, then you will see a splash screen after power-on that will inform you that you can press either R or A. Only press A if you have at least 16MB of RAM, because it copies ROM into RAM, allowing you to save files (until power OFF).
- Enjoy your newly created ROM SIMM!
I also found one of my old emails where I had created a custom System 6.0.8 disk image packed with nice apps, specifically for use on the Kero's Mac Mods 2MB ROM SIMM. I used FC8 compression to pack more content than would otherwise fit without compression. (No custom Happy Mac icon though.) It contains 4 individual files for flashing just as my 11 steps above describe:
https://tinyurl.com/4j9246ww