CPU memory map
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Virtual address space
| Address | Purpose |
|---|---|
| $2000-$20FF | Zero page |
| $2100-$21FF | Stack |
| $FFF6-$FFF7 | IRQ2/BRK vector |
| $FFF8-$FFF9 | IRQ1 vector |
| $FFFA-$FFFB | Timer vector |
| $FFFC-$FFFD | NMI vector |
| $FFFE-$FFFF | Reset vector |
The zero page, stack, and vectors exist at fixed locations within the virtual address space. The physical memory backing these can be swapped to any bank at any time, but the virtual addresses cannot be changed. The rest of the virtual address space has no special meaning to the hardware.
Physical address space
The physical address space varies by console type. The following mapping applies to the PC Engine, CoreGrafx, CoreGrafx II, and TurboGrafx-16. Differences and additions to this in other variants are documented in sections below.
| Bank | Device |
|---|---|
| $00-$7F | HuCard |
| $80-$F7 | (unmapped) |
| $F8 | RAM (8 KiB) |
| $F9-$FB | RAM mirrors |
| $FC-FE | (unmapped) |
| $FF | Hardware registers |
| Bank $FF offset | Device |
|---|---|
| $0000-$03FF | VDC (4 registers mirrored) |
| $0400-$07FF | VCE (8 registers mirrored) |
| $0800-$0BFF | PSG |
| $0C00-$0FFF | Timer (2 registers mirrored) |
| $1000-$13FF | I/O port (1 register mirrored) |
| $1400-$17FF | Interrupt controller (4 registers mirrored) |
| $1800-$1FFF | (unmapped) |
Any unmapped address in physical memory can potentially be mapped by an expansion port device or a HuCard, but most HuCards lack any sort of memory mapper and simply use the highest address bit as a chip enable.
SuperGrafx
| Bank | Device |
|---|---|
| $F8-$FB | RAM (32 KiB) |
| Bank $FF offset | Device |
|---|---|
| $0000-$0007 | VDC1 registers |
| $0008-$000F | VPC registers |
| $0010-$0017 | VDC2 registers |
| $0018-$001F | (unmapped) |
| $0020-$03FF | Mirrors of $0000-$001F |
