CPU memory map

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.

Bank	PC Engine	SuperGrafx	PC Engine CD
$00-$7F	HuCard
$80-$87	(unmapped)		RAM (64 KiB)
$88-$F7	(unmapped)
$F8	RAM (8 KiB)
$F9-$FB	RAM mirrors	RAM (24 KiB)
$FC-FE	(unmapped)
$FF	Hardware registers

Note that a PC Engine CD can be connected to the SuperGrafx as well - created a layout in which both the PC Engine CD's 64 KiB of additional RAM and the SuperGrafx's 24 KiB of additional RAM are available.

Hardware register bank

PC Engine

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 $FF offset	Device
$0000-$0007	VDC1 registers
$0008-$000F	VPC registers
$0010-$0017	VDC2 registers
$0018-$001F	(unmapped)
$0020-$03FF	Mirrors of $0000-$001F

PC Engine CD

Bank $FF offset	Device
$1800-$180F	CD interface registers

TODO: Do any mirrors exist?