Hardware vectors

Hardware vectors are a group of pointers that define how the SNES should handle certain interrupts within the ROM. Each vector is two bytes in size and point to instructions located in bank $00. The hardware vectors are grouped by the two modes of the SNES: "emulation mode" vectors and "native mode" vectors.

Native mode vectors

These vectors come into play when the SNES runs in native mode (E=0).

ROM address	Vector	Additional notes
$00:FFE0	Unused
$00:FFE2	Unused
$00:FFE4	COP vector	Triggered by the COP opcode
$00:FFE6	BRK vector	Triggered by the BRK opcode
$00:FFE8	ABORT vector	Unused by the SNES
$00:FFEA	NMI vector	Triggered by the SNES V-Blank Interrupt
$00:FFEC	Unused
$00:FFEE	IRQ vector	Triggered by the SNES H/V-Timer or external interrupt

Emulation mode vectors

These vectors come into play when the SNES runs in emulation mode (E=1).

ROM address	Vector	Additional notes
$00:FFF0	Unused
$00:FFF2	Unused
$00:FFF4	COP vector
$00:FFF6	Unused
$00:FFF8	ABORT vector	Unused by the SNES
$00:FFFA	NMI vector
$00:FFFC	RESET vector	Triggered by SNES soft/hard reset
$00:FFFE	IRQ/BRK vector	It's possible to differentiate between the two using the BRK flag

Example setup

Here's an example setup with the most commonly used vectors, which can be used in homebrew SNES ROMs. Note that the labels must be located in bank $00 (which is located within the same bank as this setup).

ORG $00FFE0

; Native mode
dw $FFFF           ; Unused
dw $FFFF           ; Unused
dw $FFFF           ; COP
dw $FFFF           ; BRK
dw $FFFF           ; ABORT
dw NativeNMI       ; NMI
dw $FFFF           ; Unused
dw NativeIRQ       ; IRQ

; Emulation mode
dw $FFFF           ; Unused
dw $FFFF           ; Unused
dw $FFFF           ; COP
dw $FFFF           ; Unused
dw $FFFF           ; ABORT
dw $FFFF           ; NMI
dw Reset           ; RESET
dw $FFFF           ; IRQ/BRK

Because homebrew programmers generally want to run their program in native mode, all vectors in emulation mode, save for reset, have been ignored. Furthermore, nothing is done with the BRK and COP vectors as these are opcodes which generally are unused.