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) |