Sometimes I want to show how old 8 bit computers work for some n00bs. It is nice to load some game from tape, some from disk. But when I want to show more game, best thing is cartridge. And not single universal cartridge, but a pile of them. This looks more “expensive” and cool.
Another reason- cheap PCB and that I wanted to to in this way.
And main reason for cartridge is speed- just put in and power on. I never liked this game.
This universal PCB for Commodore 64 cartridge. For more advance cartridges there is mandatory to add two chips- simple logic and flip-flop. I used single chip- GAL or PALCE. I have several of these and have programmer. For standard 8K or 16K games there is no need for additional chips. Only some jumpers and two diodes.
I had always problems with 3D positioning my designs. Sometime I am building mirror or upside down versions. At this time everything is ok and cartridge fits properly.
Maybe there is question why I put two resistors on clock line. There is rummors, that on some models of computers is good to place proper TTL termination on F2 (CPU clock) line.