Namco Pac-Man/Custom IC Pinouts

The Namco Pac-Man logic board features a pair of custom integrated circuits manufactured by Fujitsu for Namco, perhaps intended to deter reverse-engineering and prevent piracy of the logic board. However, this didn't prevent bootlegging of the hardware by other companies.

NVC285 - Z80 Sync Bus Controller
The NVC285 controls the passage of data between the Z80's CPU data bus (D0-D7) and the buffered data bus (DB0-DB7), synchronizes the CPU with RAM and internally holds a value used for the interrupt vector. .---\/---.  6M* -> |01    28| -- VCC 1H -> |02   27| <- /CS 2H -> |03   26| <- /M1 DB4 <> |04   25| <> D4   DB3 <> |05    24| <> D3   DB5 <> |06    23| <> D5   DB6 <> |07    22| <> D6   DB2 <> |08    21| <> D2   DB7 <> |09    20| <> D7   DB0 <> |10    19| <> D0   DB1 <> |11    18| <> D1    CK <- |12    17| <- /WREQ R/W <- |13   16| <- /RD GND -- |14   15| <- /IORQ `'

NVC284 - VRAM Addresser
The NVC284 controls how the Tilemap and Color values in Video RAM are addressed to display the playfield. It is used to synchronize the Video and Work RAM with system timing, and to flip the playfield when in the game is in cocktail table mode.

.---\/---.   2H -> |01    28| -- VCC 4H -> |02   27| <- FLIP 8H -> |03   26| -> AB0 16H -> |04   25| -> AB1 32H -> |05   24| -> AB2 64H -> |06   23| -> AB3 128H -> |07   22| -> AB4 /256H -> |08   21| -> AB5 8V -> |09   20| -> AB6 16V -> |10   19| -> AB7 32V -> |11   18| -> AB8 64V -> |12   17| -> AB9 128V -> |13   16| -> AB10 GND -- |14   15| -> AB11 `'

Discrete logic replacements
Likely due to the success of Pac-Man in the states, Fujitsu couldn't keep up with the demand for these custom ICs. Therefore small circuit boards with discrete 74-series logic replicating their functionality were often used as replacements. These replacements are common on Midway Pac-Man boards. This also made it easier for bootleg copies of Pac-Man boards to be distributed.