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5-3

Z380

™

USER'S MANUAL

ZILOG

DC-8297-03

5.2.7 Condition Codes

The Carry, Zero, Sign, and Parity/Overflow flags are used

to control the operation of the conditional instructions. The

operation of these instructions is a function of the state of

one of the flags. Special mnemonics called condition

codes are used to specify the flag setting to be tested

during execution of a conditional instruction; the condition

codes are encoded into a 3-bit field in the instruction

opcode itself.

Table 5-1 lists the condition code mnemonic, the flag

setting it represents, and the binary encoding for each

condition code.

Table 5-1. Condition codes

Condition Codes for Jump, Call, and Return Instructions

Mnemonic Meaning Flag Setting Binary Code

NZ Not Zero* Z = 0 000

Z Zero* Z = 1 001

NC No Carry* C = 0 010

C Carry* C = 1 011

NV No Overflow V = 0 100

PO Parity Odd V = 0 100

V Overflow V = 1 101

PE Parity Even V = 1 101

NS No Sign S = 0 110

P Plus S = 0 110

S Sign S = 1 111

M Minus S = 1 111

*Abbreviated set

Condition Codes for Jump Relative and Call Relative Instructions

Mnemonic Meaning Flag Setting Binary Code

NZ Not Zero Z = 0 100

Z Zero Z = 1 101

NC No Carry C = 0 110

C Carry C = 1 111

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