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Outi – Zilog Z08470 User Manual

Page 318

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Z80 Instruction Set

UM008007-0715

306

Z80 CPU
User Manual

OUTI

Operation

(C) ← (HL), B ← B – 1, HL ← HL + 1

Op Code

OUTI

Operands

None.

Description

The contents of the HL register pair are placed on the address bus to select a location in
memory. The byte contained in this memory location is temporarily stored in the CPU.
Then, after the byte counter (B) is decremented, the contents of Register C are placed on
the bottom half (A0 through A7) of the address bus to select the I/O device at one of 256
possible ports. Register B can be used as a byte counter, and its decremented value is
placed on the top half (A8 through A15) of the address bus. The byte to be output is placed
on the data bus and written to a selected peripheral device. Finally, the register pair HL is
incremented.

Condition Bits Affected

S is unknown.

Z is set if B – 1 = 0; otherwise, it is reset.

H is unknown.

P/V is unknown.

N is set.

C is not affected.

M Cycles

T States

4 MHz E.T.

4

16 (4, 5, 3, 4)

4.00

1

1

0

0

1

1

1

1

ED

1

0

0

1

1

0

1

0

A3

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