Z80 asm to hex guide

This guide should be useful for those who want to hack SMS/GG ROMS in a hex editor. This also goes for GB ROMs for the most part, though some instructions and registers are missing from the GB Z80 instruction set that are part of the Zilog Z80 instruction set. I might add the binary value of each instruction in the future. Note: not every instruction is documented yet, and some need to be edited.


Hex z80 instruction description


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F3 di disable interrupts


ED56 im interrupt mode (in this case 1)


DB in increment data


3C inc


FE cp compare


FA jr jump relative


C3 jp jump


BF ld load


87 add add


3A a accumulator


(3E while data is being stored here ex: ld (0bh),a)


CD call call subroutine


6E l register l


F5 push push data onto stack pointer note: 10 is decresed each time a value


is pushed to the stack in hex, so the next value of


data to be pushed onto the stack would be E5 and so on


FD af accumulator/flag registers


31 sp stack pointer


00 nop no operation (obviously :V)


44 b register b


65 h register h


EE xor extended or


CB iy register iy


D3 out output to port


DD ix register ix


E6 and


F0 bit bit set


F6 or or :V


FD iy register iy


21 z zero flag


36 hl registers (ex: ld (hl),00h)


FB ei enable interrupts


D6 sub subtract


FF rst restart


D9 reti return from interrupt