Zilog Z08470 - Manual (Page 276)

Z80 Instruction Set UM008007-0715
264
Z80 CPU
User Manual
JR C, e
Operation
If C = 0, continue

If C = 1, PC ← PC+ e
Op Code
JR
Operands
C, e
Description
This instruction provides for conditional branching to other segments of a program
depending on the results of a test on the Carry 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 flag = 0, the next instruction executed is taken from the location following this
instruction. If condition is met
If condition is not met:
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 1 0 0 0 1 1 38
e–2