NTDEC8801 pinout

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Revision as of 13:30, 22 February 2020 by Krzysiobal (talk | contribs) (Created page with "Category: pinouts .---\/---. VCC -- | 01 16 | -- GND /WRA000 -> | 02 15 | ?? NC NC ?? | 03 14 | ?? NC /RESET -> | 04 13 | -> A13 /WR80...")
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            .---\/---.
     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)