Zilog Z08470 - Manual (Page 274)

Z80 Instruction Set UM008007-0715
262
Z80 CPU
User Manual
JR e
Operation
PC ← PC + e
Op Code
JR
Operand
e
Description
This instruction provides for unconditional branching to other segments of a program. 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. This jump is mea-
sured 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.
Condition Bits Affected
None.
Example
To jump forward five locations from address 480, the following assembly language state-
ment is used:
JR $+5
The resulting object code and final Program Counter value is shown in the following table:
M Cycles T States 4 MHz E.T.
3 12 (4, 3, 5) 3.00
0 0 1 0 0 0 0 1 18
e–2