Ret cc – Zilog Z08470 User Manual
Page 295
UM008007-0715
Z80 Instruction Description
Z80 CPU
User Manual
283
RET cc
Operation
If cc true: PCL ← (sp), pCH ← (sp+1)
Op Code
RET
Operand
cc
Description
If condition cc is true, the byte at the memory location specified by the contents of the
Stack Pointer (SP) Register pair is moved to the low-order eight bits of the Program Coun-
ter (PC). The SP is incremented and the byte at the memory location specified by the new
contents of the SP are moved to the high-order eight bits of the PC. The SP is incremented
again. The next op code following this instruction is fetched from the memory location
specified by the PC. This instruction is normally used to return to the main line program at
the completion of a routine entered by a CALL instruction. If condition cc is false, the PC
is simply incremented as usual, and the program continues with the next sequential
instruction. Condition cc is programmed as one of eight status that correspond to condition
bits in the Flag Register (Register F). These eight status are defined in the following table,
which also specifies the corresponding cc bit fields in the assembled object code.
cc
Condition
Relevant
Flag
000
Non-Zero (NZ)
Z
001
Zero (Z)
Z
010
Non Carry (NC)
C
011
Carry (C)
C
100
Parity Odd (PO)
P/V
101
Parity Even (PE)
P/V
110
Sign Positive (P)
S
111
Sign Negative (M)
S
1
1
0
0
0
cc