Out (n), a – Zilog Z08470 User Manual
Page 315
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UM008007-0715
Z80 Instruction Description
Z80 CPU
User Manual
303
OUT (n), A
Operation
(n) ← A
Op Code
OUT
Operands
(n), A
Description
The operand n is placed on the bottom half (A0 through A7) of the address bus to select
the I/O device at one of 256 possible ports. The contents of the Accumulator (Register A)
also appear on the top half (A8 through A15) of the address bus at this time. Then the byte
contained in the Accumulator is placed on the data bus and written to the selected periph-
eral device.
Condition Bits Affected
None.
Example
If the Accumulator contains
23h
, then upon the execution of an OUT (
01h
) instruction,
byte
23h
is written to the peripheral device mapped to I/O port address
01h
.
M Cycles
T States
4 MHz E.T.
3
11 (4, 3, 4)
2.75
1
1
1
1
1
0
0
0
D3
n
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