Namco NB-1
The Namco 32-bit NB-1 arcade system board was first used by Namco in 1993. NB-2 has different memory map, more complex sprite and tile banking and 2 additional ROZ layers than NB-1.
Read more about Namco NB-1: Namco NB-1/NB-2 Specifications, Namco NB-1 PCB, List of Namco NB-1 Arcade Games, List of Namco NB-2 Arcade Games