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Keyboard processor (80C49) signal functions
Table
11- 2
Pin No
.
Signal name
IN/OUT
Description
1
2
TO
XTALt
IN
IN
Data or READY signal
input
from the System Unit
"
;
Accepts a quartz signal16MHz) for the internal clock oscillator.
3
XTAL2
IN
Äccepts a Quartz signal16MHz) for the interna I clock oscillator
.
4
RESET
IN
Initialization input
of BOC49
5
SS
IN
+5V
6
7
INT
EA
IN
IN
CPU interrupt strobe input ISTC)
GND
,
B
RD
-
N.C
9
PSEN
-
N.C
~
10
WR
-
N.C
11
ALE
-
N.C
12
19
DBO
DB7
IN
Returns signals from the keyboard.
20
Vss
IN
GND
21
P20
OUT
Send data to the System Unit lOK)
22
P21
OUT
Data enable/start
signal
(SRK) to CPU
23
P22
OUT
Enables
data
send
to the mouse ICTS)
24
P23
-
N.C
25
PROG
-
N.C
26
VDD
IN
+5V
27
30
Pl0
P13
OUT
Strobe to the keyboard.
31
P14
OUT
CAPS indi.!:ator drive signal
".
32
P15
OUT
GRAPH indicator drive signal
33
P16
OUT
N.C
34
P17
-
N.C
35
P24
-
N.C
36
.
37
.
38
P25
P26
P27
-
-
-
N.C
N.C
N.C
_.
...
39
Tl
IN
"
Mouse data input (TX
0)
40
Vcc
IN
+5V
power supply
~~
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