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The X86 Microprocessors: Architecture and Programming (8086 to Pentium), 1st Edition
book

The X86 Microprocessors: Architecture and Programming (8086 to Pentium), 1st Edition

by Lyla B. Das
May 2024
Intermediate to advanced content levelIntermediate to advanced
665 pages
23h 2m
English
Pearson India
Content preview from The X86 Microprocessors: Architecture and Programming (8086 to Pentium), 1st Edition
PERIPHERAL INTERFACING  I 307
D
7
D
6
D
5
D
4
D
3
D
2
D
1
D
0
I/O I/O IBF
A
INTE
A
INTR
A
INTE
B
OBF
B
INTR
B
us the status of Port C will be as shown.
What is needed, is to read in Port C and test the condition of D
5
for knowing the status of IBF
A
.
Test the condition of D
1
for the status of OBF
B
IN AL, PORTC ;read in the contents of Port C
TEST AL, 5 ;for testing the condition of D
5
, IFB
A
TEST AL, 1 ;for testing the condition of D
1
, OFB
B
PC
4, 5
PORT A – (STROBED OUTPUT)
PORT B – (STROBED INPUT)
RD
8
8
1=INPUT
0=OUTPUT
PA7–PA0
PC
7
PC
6
PC
3
PC
4, 5
PB7–PB0
PC
2
PC
1
PC
0
WR
CONTROL WORD
110 11/001
D7
D6
D5
D4
D3
D2
D1
D0
INTR
A
I/O
INTR
B
IBF
B
STB
B
OBF
A
ACK
A
Figure 9.16 | Port A in strobed output ...
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Publisher Resources

ISBN: 9781282663169