Namco System 11, System 12 (and System 10?)
Capcom/Sony ZN-1, ZN-2
Konami GV, Konami GQ
Taito FX-1A, Taito FX-1B
Atlus PSX, PS Arcade 95, Tecmo TPS
Same as in PSX. Except, one board is said to be having the CPU clocked at
48MHz, instead of 33MHz???
Same as in PSX. Except, most or all boards are said to have 2MB VRAM instead of
1MB. Unknown how the extra VRAM is accessed... maybe as Y=512..1023... (though
the PSX VRAM transfer commands are limited to 9bit Ysiz values, but maybe Y
coordinates can be 10bit wide).
Arcade games are stored on ROM (or FLASH) instead of using CDROM drives.
Most PSX-based arcade boards are having the PSX-SPU replaced by a different
sound chip (with each arcade manufacturer using their own custom sound chip,
often controlled by a separate sound CPU).
Arcade boards are typically having digital joysticks instead of joypads, with
differently named buttons (instead of /,[],(),><), probably accessed via
custom I/O ports (instead of serial transmission)? Plus additional coin inputs
and DIP switches.
Note: There's no documentation for those arcade boards yet, however, it might
be possible to extract that info from MAME source code.