Register	Type	Description
rg0-rgf	General Purpose	General-purpose registers.
acc	Special	Accumulator for calculations and temporary storage - don't use this for variables as pseudo instructions may overwrite this implicitly!
spr	Special	Stack pointer
bpr	Special	Base pointer for stack frames
ret	Special	Return address register
idr	Privileged	Interrupt descriptor table address on-read/write: protection fault (unless in kernel mode)
mmr	Privileged	Hardware memory map table address on-read/write: protection fault (unless in kernel mode)
zero	Read-only	Always contains zero on-read: always returns zero on-write: value is voided
pcx	Read-only	Program counter on-write: protection fault
noreg	Placeholder	Indicates absence of register argument on-read/write: illegal instruction fault