Zilog Z80380 - Manual (Page 176)

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Z380 ™
U SER ' S M ANUAL
DC-8297-03
Z ILOG
RETI
RETURN FROM INTERRUPT
RETI
Operation: if (XM) then begin
PC(7-0)
←
(SP)
PC(15-8)
←
(SP+1)
PC(23-16)
←
(SP+2)
PC(31-24)
←
(SP+3)
SP
←
SP + 4
end
else begin
PC(7-0)
←
(SP)
PC(15-8)
←
(SP+1)
SP
←
SP + 2
end
This instruction is used to return to a previously executing procedure at the end of a
procedure entered by an interrupt. The contents of the location addressed by the Stack
Pointer (SP) are popped into the Program Counter (PC), thereby specifying the location of
the next instruction to be executed. A special sequence of bus transactions is performed
when this instruction is executed in order to control Z80 family peripherals; see the
description of the external interface for more details.
Flags: S: Unaffected
Z: Unaffected
H: Unaffected
V: Unaffected
N: Unaffected
C: Unaffected
Addressing Execute
Mode Syntax Instruction Format Time Note
RETI 11101101 01001101 2+r X