org &0000 ;execution resets here after the 68000 resets the Z80 and sends a bus request.
jr start

org &0038 ;in IM 1 mode, we jump here for an IRQ. But this isn't being used for this example, so we'll just silently return.
reti

org &0060
start:
DI
IM 1
LD SP,&2000


main:         ;hardware non-maskable interrupt (NMI) jumps here (address &0066)

ld a,(&1F00)  ;we'll only allow the 68000 to alter the contents of this memory address.
or a
jr z,main     ;just keep looping until it's nonzero.

;by counting the bytes each instruction takes, it can be proven that this label points to &006C.
;The call opcode takes 1 byte and the operand that follows takes two bytes.

smc:
call &0000    ;we'll overwrite the operand at &006D-&006E with whatever function we want to call.

done:
jp done       ;loop until next reset

ExampleFunction:   ;ADDR: &0072($A00072)
ret                ;for simplicity this does nothing but in reality you'd have it do something sound-related here.