ROM-Only boards
Some late boards made by SNK-Playmore are standalone NeoGeo systems with embedded game ROMS.
Particularities
The game ROMs are labelled with their NGH number and data type, like in cartridges but without any manufacturer numbers.
Chips used
Those boards are known to use the NEO-YSA2 audio subsystem chip, NEO-GRZ graphics chip, NEO-PCM2, NEO-CMC (90G06CF7042) and NEO-PVC banking chips.
See [this list] for board scans.