V810
From Archaic Pixels
The RISC CPU used in the PC-FX clocked at 21.477MHz.
The V810 CPU memory bus in the PC-FX runs in 16-bit mode(versus 32-bit mode).
CPU Memory Map
| Memory range | R/W | Description |
| $00000000-$001FFFFF | R/W | 1MB Internal RAM |
| $80000000-$80000FFF? | R?/W? | Possibly a mirror of the I/O port map. |
| $80700000-$807FFFFF | R | "EXTIO" boot ROM. |
| $A0000000-$A3FFFFFF | R | HuC6261 (VCE) Palette RAM Data Port Read, intended for use with bitstring instructions. |
| $A4000000-$A7FFFFFF | R | HuC6270 (VDC-A) VRAM Data Port Read, intended for use with bitstring instructions. |
| $A8000000-$ABFFFFFF | R | HuC6270 (VDC-B) VRAM Data Port Read, intended for use with bitstring instructions. |
| $AC000000-$AFFFFFFF | R | HuC6272 (KING) KRAM Data Port Read, intended for use with bitstring instructions. |
| $B0000000-$B3FFFFFF | W | HuC6261 Palette RAM Data Port Write, intended for use with bitstring instructions. |
| $B4000000-$B7FFFFFF | W | HuC6270 (VDC-A) VRAM Data Port Write, intended for use with bitstring instructions. |
| $B8000000-$BBFFFFFF | W | HuC6270 (VDC-B) VRAM Data Port Write, intended for use with bitstring instructions. |
| $BC000000-$BFFFFFFF | W | HuC6272 (KING) KRAM Data Port Write, intended for use with bitstring instructions. |
| $E0000000-$E7FFFFFF | R/W | 32KB Internal Backup RAM. Not present on the PC-FXGA. It is apparently 8-bit RAM, so the upper byte on 16-bit writes is ignored, and the address into the RAM is calculated like: (Address >> 1) & 0x7FFF |
| $E8000000-$EFFFFFFF | R/W | External Backup RAM |
| $FFF00000-$FFFFFFFF | R | 2MB BIOS ROM |
CPU I/O Port Map
| Port range | R/W | Description |
| $00000000-$000000FF | R/W | Keyport. |
| $00000100-$000001FF | W | HuC6230 (SoundBox) |
| $00000200-$000002FF | W | HuC6271 (RAINBOW) |
| $00000300-$000003FF | R/W | HuC6261 (VCE) |
| $00000400-$000004FF | R/W | HuC6270 (VDC-A) |
| $00000500-$000005FF | R/W | HuC6270 (VDC-B) |
| $00000600-$000006FF | R/W | HuC6272 (KING) |
| $00000700-$0000071F | W | Expansion bus reset register(D0 = 1, reset? level sensitive?) |
| $00000C00-$00000C3F | R | HuC6270 (VDC-A) "address keep register" |
| $00000C40-$00000C7F | R | HuC6270 (VDC-B) "address keep register" |
| $00000C80-$00000CBF | R/W | Backup Memory Control |
| $00000CC0-$00000CFF | R | "Gatearray version register" |
| $00000E00-$00000EFF | R/W | IRQ Control |
| $00000F00-$00000FFF | R/W | Timer Control |
| $80500000-$80510000 | R/W | HuC6273 (3D) |
