Zilog Z08470 - Manual (Page 278)

Z80 Instruction Set UM008007-0715
266
Z80 CPU
User Manual
JR NC, e
Operation
If C = 1, continue

If C = 0, PC ← PC + e
Op Code
JR
Operands
NC, 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 is equal to 0, the value of
displacement 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 automatically adjusts for the twice incremented PC.
If the flag = 1, the next instruction executed is taken from the location following this
instruction.
If the condition is met:
If the 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.
7 7 (4, 3) 1.75
0 0 1 0 0 0 1 0 30
e–2