Z8
®
CPU
User Manual
UM001604-0108 Instruction Description
218
Return
Syntax
RET
Instruction Format
Operation
PC ← @SP
SP ← SP + 2
This instruction is normally used to return from a procedure entered by a CALL instruc-
tion. The contents of the location addressed by the SP are popped into the PC. The next
statement executed is the one addressed by the new contents of the PC. The stack pointer
is also incremented by two.
Each PUSH instruction executed within the subroutine should be countered with a POP
instruction in order to guarantee the SP is at the correct location when the RET instruction
is executed. Otherwise the wrong address is loaded into the PC and the program does not
operate as appropriate.
Example
If SP contains 2000h, external data memory location 2000h contains 18h, and location
2001h contains B5h, the statement:
RET
Op Code: AF
leaves the value 2002h in the SP, and the PC contains 18B5h, the address of the next
instruction to be executed.
Cycles
OPC
(Hex)
OPC 14 AF
Flag Description
C Unaffected
Z Unaffected
S Unaffected
V Unaffected
D Unaffected
H Unaffected
Note:
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