NTDEC8801 pinout
.—/—. VCC – | 01 16 | – GND /WRA000 -> | 02 15 | ?? NC NC ?? | 03 14 | ?? NC /RESET -> | 04 13 | -> A13 /WR8000 -> | 05 12 | <- CPU-/ROMSEL /WR8000 -> | 06 11 | <- CPU-A13 CNTRESET <- | 07 10 | ?? NC NC ?? | 08 09 | – +5V ‘——–’ NTDEC8801
This chip was used in at least one of SMB2J pirate ports (mapper 40)[1]. There exist exactly the same SMB2J port without this chip but with additional 74’s IC [2], so NTDEC8801 is aggregate the function of:
- flip flop with set/reset: CNTRESET <= 0 when /WRA000=0 else ‘1’ when /WR8000=0
- multiplexer with negation: A13 <= CPU-A13 when CPU-!ROMSEL! = 0 else not CPU-A13
- and something more that is not used (not wired)