Dottori-kun: the basic, disposable games that came with Japanese arcade cabinets to comply with regulations

Sega's Dottori-Kun and Taito's Mini-Vaders are examples of the basic arcade games included with re-usable cabinets in Japan in the early 1990s, to comply with regulations that called for something playable. They functioned like the photos included with frames: pop them out of the Jamma slot, throw them away, slot in a real game board. Now, of course, they're collectors' pieces. Nicole Branagan writes:

It looks like this is a 4.00MHz Z80 computer with 2KB of RAM; by comparison, the 1977 TRS-80 Model 1 had a 1.77MHz Z80 and started at 4KB of RAM. So these specs aren't at all impressive for 1990; but of course, this was a computer designed to be thrown away. Still, that CPU and its clock speed are the same as that in the Sega Master System, which was still a going concern at the time, and it has as much RAM as the work RAM on the base Nintendo Entertainment System.

They are implemented in MAME, if you want to check them out! And here's Chris McCovell on dottori-kun hacking.