In r (c) – Zilog Z08470 User Manual
Page 305
UM008007-0715
Z80 Instruction Description
Z80 CPU
User Manual
293
IN r (C)
Operation
r ← (C)
Op Code
IN
Operands
r, (C)
Description
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. The contents of Register B are
placed on the top half (A8 through A15) of the address bus at this time. Then one byte
from the selected port is placed on the data bus and written to register r in the CPU. Regis-
ter r identifies any of the CPU registers shown in the following table, which also indicates
the corresponding 3-bit r field for each. The flags are affected, checking the input data.
Register
r
Flag
110
Undefined op code; set the flag
B
000
C
001
D
010
E
011
H
100
L
101
A
111
M Cycles
T States
4 MHz E.T.
3
12 (4, 4, 4)
3.00
1
1
0
0
1
1
1
1
EB
0
1
r
0
0
0