Zilog Z08470 - Manual (Page 280)

Z80 Instruction Set UM008007-0715
268
Z80 CPU
User Manual
JR Z, e
Operation
If Z = 0, continue

If Z = 1, PC ← PC + e
Op Code
JR
Operands
Z, e
Description
This instruction provides for conditional branching to other segments of a program
depending on the results of a test on the Zero Flag. If the flag = 1, the value of displace-
ment e is added to the Program Counter (PC) and the next instruction is fetched from the
location designated by the new contents of the PC. The jump is measured from the address
of the instruction op code and contains a range of –126 to +129 bytes. The assembler auto-
matically adjusts for the twice-incremented PC.
If the Zero Flag = 0, the next instruction executed is taken from the location following this
instruction.
If this condition is met, the following data results:
If this condition is not met, the following data results:
Condition Bits Affected
None.
M Cycles T States 4 MHz E.T.
3 12 (4, 3, 5) 3.00
M Cycles T States 4 MHz E.T.
2 7 (4, 3) 1.75
0 0 0 0 0 0 1 1 28
e–2