Using runtime zeropage locations in assembly language

The runtime zeropage locations used by the compiler are declared in the assembler include file zeropage.inc.

location	size	meaning	usage
sp	2	stack pointer	access the parameter stack
tmp1..tmp4	1 ea.	temporary value	can be written to at any time (caller saved)
ptr1..ptr4	2 ea.	pointer	can be written to at any time (caller saved)
sreg	2	secondary register	can be written to at any time (caller saved)
regsave	4	register save area	can be written to at any time (caller saved)
regbank	6	register bank	can be used only after saving (callee saved)