Summary

After I designed a replica of the original cartridge, I decided to make my own PCB. Since I still had a bunch of 27C128s laying around (and you can still get them at Aliexpress), I drew up a board. And then I discovered that a 27C128 is much wider than the available space betweens the internal posts in the original cartridge :-( The original PCB just had the die with a blob of goop on top.

So instead of redrawing the PCB I made some mods to the cartridge. This one is easier to print without supports, as I didn't stick to the original guts. The outside remains the same. The original silicone sleeve does also fit. Use CA glue to glue both parts together.

Nice thing is that you have access to the ROM from the back of the cartridge. If you don't use a DIP socket, the EPROM is flush with the back, so you can cover it up with a home-brew sticker. If you use a socket you can swap the ROMs out. I made one with a Textool socket, so I can easily swap out test ROMs that don't need a permanent enclosure.

Print Settings

Rafts:

No

Supports:

No

Resolution:

0.2mm

Infill:

20% should be fine

Filament:

colorFabb PLA/PHA black

Notes:

Print this model upside down. No support is needed if your printer can handle bridging.