5.2.3
Address decode & D/O CKT
VCC
C3
10u
C1210
C1
.1u
C0805
J1
CON20A
JDIP20P
2
4
6
8
J2
CON20A
JDIP20P
U2
74LS273
SOL20
11
1
D8
Q8
CLK
CLR
U1
74HCT138
SOIC16
1
2
3
6
4
5
15
14
13
12
11
10
9
7
A
B
C
G1
G2A
G2B
Y0
Y1
Y2
Y3
Y4
Y5
Y6
Y7
C2
.1u
C0805
U3
74LS273
SOL20
7
6
8
9
13
12
14
15
17
16
18
19
11
1
D2
Q2
D3
Q3
D4
Q4
D5
Q5
D6
Q6
D7
Q7
D8
Q8
CLK
CLR
GND
GND
GND
VCC=20
GND=10
VCC=16
GND=8
outportb(0)
outportb(1)
The CS\ will be active if program input/output from I/O address BASE+0 to
BASE+0xff.
Write value_1 to DO 0 to 7
outportb (BASE+0, value_1);
Write value_2 to DO 8 to 15
outportb (BASE+1, value_2);
The power-up default value of BASE is 0.
It is
not
recommended to change the value of BASE from 0 to another value.
I/O Expansion Bus for 7188X/7188E User’s Manual, Jan/2005 v1.5, 7PH-000-15---27