Brain Board

A ROM card for the Apple II that can, among other things, enable Apple I compatibility:

https://www.willegal.net/appleii/brainboard.htm

I imported the published gerbers into a PCB and reverse-engineered the schematic from the PCB, as the schematic provided in the manual is of such low resolution as to be useless. The only functional change to the PCB was to reduce signal trace widths from a rather fat 0.635 mm to a more reasonable 0.25 mm and to replace the ground and power traces with zone fills. I suspect the ground zone fill will take care of this problem.

A zipball with the updated gerbers is under the jlcpcb directory. There are also BOM and component-rotation files, but rotations haven't been verified as most components weren't available from JLCPCB as of 11 July 2025. A schematic PDF is also included for quick reference, and a STEP model of the board is included because I can. :-)