This is a work-in-progress for a break-out cartridge for the vintage "V-Tech Genius Leader" series of children's learning computers.
Currently, the debug cartridge latches onto the bus at a given memory address and allows for a simple 1-byte I/O. I have created a FTDI-USB terminal connection to a Raspberry Pi and a proof-of-concept MIDI port using these designs :-)
I also included my crappy PCB designs in the hope that someone with better KiCAD skills will create a usable version that is suitable for sending to a PCB manufacturer.
Use the 3D printable cartridge case to make it look "legit". There is also an Illustrator file for that sweet, sweet Genius Leader label design :-)
There is also some compiler support for the Genius Leader in the z88dk compiler suite. See https://www.z88dk.org/forum/viewtopic.php?pid=16831 for discussions about that.
Help and improve this and let's make a nice plug-and-play debugging cartridge for these inexpensive computers!