Signals

Name	Description	Type	Polarity	Comes from	Fault consequence
24M	24MHz master clock	Clock		NEO-D0	Nothing works
12M	12MHz clock (24/2) non-inverted	Clock		NEO-D0	Bad graphics

• 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 (always 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 ROMs 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, used to slow down acces to memory (see wait cycles)
• FIXD0~FIXD7: Fix layer data bus, holds data for 2 pixels
• P0~P23: C ROM, S ROM, LO ROM and internal address/data bus (multiplexed P bus)
• PA0~PA11: Palette RAM address bus
• PAL: Palette RAM address decode for 68k access
• PCK1B: Low 55ns, high 610 (1.5MHz) Clock to latch C ROM address from P0~P23 (mapping) on rising edge.
• PCK2B: Low 55ns, high 610 (1.5MHz) Clock to latch S ROM address from P0~P15 (mapping) on rising edge.
• /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, see wait cycles
• 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