My dad used to work at the company that provided the chips for Atari's 2600 games. As I recall, he told me some of his chip designs also went into the video arcade (Pac-Man) games.
Anyways, he brought home an Atari 2600 console with joysticks and paddles, as well as 2 or 3 hundred games. I truly enjoyed the Atari during my childhood! I'm pretty sure I still have these games somewhere in the garage. The thing is, they don't come in cartridges. All my games are on chips (about 1/2" wide and 1" long). These chips are stored on "foamy" blocks in plastic containers. (Hence, all 2 or 3 hundred games fit in 1 or 2 shoeboxes.)
To play the games, I had several "modified" cartridges where there was a slot to put the chip into and a locking mechanism. I had several of these modified cartridges, as certain chips could only be played on certain cartridges. I'm not sure if this had to do with memory allocation, or what because some of the switches on the cartridges (the game chips were put into boxes, and the boxes were labeled with which cartridge and switches to use) were labeled with things like "4K" and "16K". Or something like that... keep in mind I haven't played with this stuff in over 10 years!
Has anyone heard about ROM collections on chips like these? I wish my Atari 2600 still worked! I would have kept playing, but the on/off switch stopped working a long time ago. I've considered buying another console, but I don't know if I'd ever really play again.