z80 - How do I find value of register and flags in Assembler? - 


 programmcode | zero-flag | sign-flag | register | register hl               |     0     |     0     |     00h    |    00 00h --------------|-----------|-----------|------------|------------ mov hl, 00ffh |           |           |            | dec hl        |           |           |            | add 81h       |           |           |            | cp          |           |           |            | sub 02h       |           |           |            |

i have part of program in mc8-assembler (the cpu of mc8 formed 8bit processor zilog z80 of training board) value going have flag after execution , whatvalue being found in register? values before execution given in first column.

can + write explanation?

what intel calls mov, zilog calls ld; otherwise can work out answer looking @ e.g. this instruction table.

mov hl, 00ffh ld hl, 00ffh in zilog terms, appropriate ld hl. it's instruction 0x21 , tells loads value hl , doesn't affect flags. that's row 1 sorted. dec hl on @ 0x2b doesn't affect flags (which catches me out, record) add a,* that's sign , 0 might change, depending on think happens a.

just each instruction in turn, see does, thing, consider flags if that's instruction affects flags.


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