Keyboard Interface Board; Circuit Diagram - UBI EasyCoder 501 Service Manual

UBI EasyCoder 501 – Service Manual
2. FRONT AND KEYBOARD, cont'd.
2.6
Keyboard Interface Board;
Circuit Diagram
+5V
10 9
P1
1 DB7
2 DB6
3 DB5
4 DB4
5 DB3
6 DB2
7 DB1
8 DB0
9 A5
10 A6
11 GND
12 GND
13 CS8255
14 WR
15 RD
16 RESET
17 ECLK
18 VDISP
19 GND
20 +5V
C2 C1
+5V
RN2 1
8 7 6 5 4 3 2
82C55
PC7
PC6
PC5
PC4
PC3
PC2
PC1
27
AD7
PC0
28
AD6
29
AD5 PB7
30
AD4 PB6
31
AD3 PB5
32
AD2 PB4
33
AD1 PB3
34
AD0 PB2
PB1 19
PB0 18
9
A0
PA7
8
A1
PA6
6
CS
PA5
36
WR
PA4
5
RD
PA3
R8
35
RESET
PA2
PA1
C3
PA0
IC1
C4
Keyboard Interface Board 1-040701-26; Circuit Diagram
+5V
P4
1
2
IC2A
1 2
1
74HC04
IC2B
9
3 4
1
74HC04
10 RW 74HC04
11 RS IC2C
11
12 ERROR 5 6
1
13 READY
74HC04
17 74HC04
16
13
15
14
74HC04
25
24
23
22
21
20
37
38
39
40
1
2
3
4
R2
IC2D
R3
8
1
READY ERROR
IC2E
LED3 LED2
10
1
IC2F
12
1
10 9
P2
1
2
RW 5
RS 4
ECLK 6
VDISP 3
DB0 7
DB1 8
DB2 9
DB3 10
DB4 11
DB5 12
DB6 13
DB7 14
POWER
LED1
+5V
RN1 1
8 7 6 5 4 3 2
A5
P3
SHIFT 1
COL6 2
COL5 3
COL4 4
COL3 5
COL2 6
COL1 7
COL0 8
ROW7 9
ROW6 10
ROW5 11
ROW4 12
ROW3 13
ROW2 14
ROW1 15
ROW0 16
19