C64/C128 MIDI flash interface
Kernal switcher for the C64/C64C/C128
Sidekick64: A Versatile Software-Defined Cartridge for the C64, C128, C16, plus/4, and VIC20
SIDKick pico is an inexpensive dual-SID-replacement for the C64 and C128
A multiple diagnostic cartridge for the Commodore C64 and/or C128
C128 80 column screen editor
Simple EPROM-based C64 and C128 cartridge PCB designs