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V810
Bob Frasure edited this page Jan 6, 2025
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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).
| 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 |
| 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) |
V810 Family Architecture