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Zero Flag
From SnesLab
The Zero Flag (Z) exists on the 65c816 as bit 1 of the status register. It indicates whether the last value computed or moved is zero: set if it is and clear if not. Although there are no dedicated SEZ or CLZ instructions to set or clear it, it can be directly set with SEP and cleared with REP. It is also affected by these 41 instructions:
- ADC
- AND
- ASL
- BIT
- CMP
- CPX
- CPY
- DEC
- DEX
- DEY
- EOR
- INC
- INX
- INY
- LDA
- LDX
- LDY
- LSR
- ORA
- PLA
- PLB
- PLD
- PLX
- PLY
- ROL
- ROR
- SBC
- TAX
- TAY
- TCD
- TCS
- TDC
- TRB
- TSB
- TSC
- TSX
- TXA
- TXY
- TYA
- TYX
- XBA
The BEQ and BNE instructions examine the zero flag to decide whether or not to branch.
The SPC700 and Super FX chips also have a zero flag.