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Aes c1.jpg
Package QFP100R
Manufacturer Logo fujitsu.jpg
First use 1992 ?
Used on NEO-AES3-4 board...

Multi-purpose keystone chip used for address decoding, inter-CPU communications, wait cycle generation, and player inputs.

Maps itself to even byte access only (only D15~8 connected).


NEO-C1 pinout.png
Edit this pinout




  • IN00: Up P1
  • IN01: Down P1
  • IN02: Left P1
  • IN03: Right P1
  • IN04: A P1
  • IN05: B P1
  • IN06: C P1
  • IN07: D P1


  • IN10: Up P2
  • IN11: Down P2
  • IN12: Left P2
  • IN13: Right P2
  • IN14: A P2
  • IN15: B P2
  • IN16: C P2
  • IN17: D P2


  • IN20: Start P1
  • IN21: Select P1
  • IN22: Start P2
  • IN23: Select P2
  • IN24: Memory card inserted
  • IN25: Memory card inserted
  • IN26: Memory card write protect
  • IN27: System type (home/arcade)


  • A17~A21: 68k address bus
  • A22I~A23I: NEO-E0 address input
  • D8~D15: 68k data bus
  • R/W,UDS,LDS,AS,DTACK: 68k bus control signals
  • 68KCLK: 12MHz 68k clock
  • ROMWAIT,PWAIT0,PWAIT1,PDTACK: signals from cart PROG board to configure how /DTACK is generated for ROMOE region (how is it configured?)

Decoded signals

The following output and write enables have an upper(U)/lower(L) byte enable signal based on /UDS and /LDS from the 68k.

  • ROMOEU,ROMOEL: $000000-$0FFFFF read, 68k program ROM on cart PROG board
  • WRU,WRL,WWU,WWL: $100000-$1FFFFF read/write, 68k user RAM
  • PORTOEU,PORTOEL,PORTWEU,PORTWEL: $200000-$2FFFFF read/write, multipurpose signal on cart PROG board
  • SRAMOEU,SRAMOEL,SRAMWEU,SRAMWEL: $D00000-$DFFFFF read/write, battery-backed RAM

The following are expected to be word accessed, byte writes and reads are ignored or do not work as expected.

  • CRDO,CRDW: $800000-$BFFFFF read/write, memory card
  • CRDC: Memory card select (CRDO AND CRDW ?)
  • LSPOE,LSPWE: $3C0000-$3DFFFF read/write, LSPC2-A2
  • PAL: $400000-$7FFFFF access, enables transcievers attached to palette RAM for 68k access

Z80 I/O

  • SDD0~SDD7: Z80 data bus used for 68k/Z80 communication
  • SDZ80R,SDZ80W: read / write signals for Z80 communication
  • SDW: signals that 68k has written a byte to Z80 port, will make NEO-D0 generate interrupt if enabled
  • SDZ80CLR: initialise stored byte to zero?