The earliest non-microprocessor based arcade system boards were designed around codeless state machine computers with the main board and any support boards consisting of discrete logic circuits comprising each element of the game itself. The next generation of arcade system boards, with the inclusion of microprocessor based technology, incorporated the game program code directly on the main system board via game code stored in ROM chips mounted on the main board.
Later arcade system boards, including the DECO Cassette System, SNK's Neo-Geo, Capcom's CPS-2, and Sega's NAOMI, separated the system board from the game program itself, akin to a home video game console and cartridge/CD/DVD/Hard Disk. This method benefitted both manufacturers and arcade game owners. Once the system board was purchased, the owner could switch out the games at a fraction of the price and with less effort, and the manufacturers could produce fewer of the costly system boards and more of the less-costly games.
Currently, the company with the record of the highest number of original arcade system boards is Sega.