Signals

From NeoGeo Development Wiki
Revision as of 09:25, 23 November 2015 by Freem (talk | contribs) (BIOS -> system ROM)
Jump to navigation Jump to search
The printable version is no longer supported and may have rendering errors. Please update your browser bookmarks and please use the default browser print function instead.
  • 24M: 24MHz master clock signal
  • 12M: 12MHz clock (24/2) non-inverted from NEO-D0
  • 8M: 8MHz clock (24/3) non-inverted from LSPC
  • 6MB: 6MHz clock (24/4) inverted from NEO-D0
  • 4M: 4MHz clock (24/6) non-inverted from LSPC
  • 4MB: 4MHz clock (24/6) inverted from LSPC+AS04
  • 1MB: 3MHz clock (24/8) inverted from NEO-D0
  • 68KCLK: 12MHz clock (24/2) non-inverted from NEO-D0 (equivalent to 12M)
  • 68KCLKB: 12MHz clock (24/2) inverted from NEO-D0
  • 2H1: S ROM A3
  • A1~A23: 68k address bus
  • A22I,A23I: A22 and A23 modified for 68k vector table swap
  • AS: 68k Address Strobe
  • BNK0~2: Memory card bank selection
  • CA4: C ROM A4
  • C* or CR0~CR31: C ROMs data bus (2*16bits), holds data for one 8 pixels line
  • D0~D15: 68k data bus
  • /DTACK: 68k Data Transmit ACKnowledge
  • FIXD0~FIXD7: S ROM data bus
  • P0~P23: C ROM, S ROM and LO ROM address/data bus (multiplexed)
  • PA0~PA11: Palette RAM address bus
  • PAL: Palette RAM address decode
  • PCK1B: Low 55ns, high 610 (1.5MHz) Clock to latch C ROM address from P0~P23 (mapping) on rising edge. Delayed with capacitor.
  • PCK2B: Low 55ns, high 610 (1.5MHz) Clock to latch S ROM address from P0~P15 (mapping) on rising edge. Delayed with capacitor.
  • /PORTADRS: $200000-$2FFFFF (P2+ ROM/Security chip) any access
  • /PORTOEL: $200000-$2FFFFF (P2+ ROM/Security chip) odd byte read
  • /PORTOEU: $200000-$2FFFFF (P2+ ROM/Security chip) even byte read
  • /PORTWEL: $200000-$2FFFFF (P2+ ROM/Security chip) odd byte write
  • /PORTWEU: $200000-$2FFFFF (P2+ ROM/Security chip) even byte write
  • /PWAIT0, /PWAIT1: adds 0 to 3 cycle delay for P2 ROM reads
  • R/W: 68k Read/Write
  • /ROMOE: $000000-$0FFFFF (P1 ROM) read
  • /ROMOEL: $000000-$0FFFFF (P1 ROM) odd byte read
  • /ROMOEU: $000000-$0FFFFF (P1 ROM) even byte read
  • /ROMWAIT: add 1-cycle delay for P1 ROM reads
  • /SROMOE: $C00000-$CFFFFF (System ROM) read
  • /SROMOEL: $C00000-$CFFFFF (System ROM) odd byte read
  • /SROMOEU: $C00000-$CFFFFF (System ROM) even byte read
  • SDA0~SDA15 : Z80 address bus
  • SDD0~SDD7: Z80 data bus
  • SDRAD0~SDRAD7: ADPCM-A ROM multiplexed bus (data/address)
  • SDRA8,SDRA9,SDRA20~SDRA23: ADPCM-A ROM address bus
  • SDPAD0~SDPAD7: ADPCM-B ROM multiplexed bus (data/address)
  • SDPA8,SDPA9,SDPA10,SDPA11: ADPCM-B ROM address bus
  • SYSTEM: low when onboard ROMs selected
  • SYSTEMB: inverted SYSTEM