From NeoGeo Development Wiki
Physical DIP switches on MVS boards used to configure various options like coin-up and multiplayer link. The switches states are read through register REG_DIPSW as a byte (0 is on).
- Switch 8: Freeze - pauses the game (done by software in a system ROM call)
- Switch 7: Enable freeplay (player start doesn't require credits)
- Switch 6: Enable communication
- Switches 4~5: Multiplayer link cab number (in binary: 1, 2, 3, 4)
- Switch 3: Enable mahjong controller
- Switch 2: Number of coin chutes (1 or 2)
- Switch 1: Bring up the system ROM menu at boot
There are no such switches on home and CD systems.