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C.P.U BLOCK DIAGRAM AND PIN ASSIGNMENT
<PORT LIST>
74HD404889
port Name Function Description Logic
2 R70/AN0 IN NiCd battery change control signal
3 R71 IN Mechanical switches L
4 R72 IN Red/Black ribbon check switch L
5 R73 IN Head position check sensor(E-30) L
6 R80 IN Card right/back side check sensor H
7 R81 IN Card right/back side check sensor H
17 D0/INT0 IN Head feed encoder sensor input(E-38)
18 D1/INT1 IN Paper feed encoder sensor input(E-37)
19 D2 OUT H
20 D3 OUT Five sensors control H
21 D4 IN AC Failure detection signal H
22 D5 IN 5V monitoring H
23 D6 OUT Time signal control H
24~26 D7~D9 OUT Six key and jumper wire scan control L
27~28 D10~D11 OUT Six LED scan control L
29 R00 OUT Paper feed motor control(Pulling) H
30 R01 OUT Paper feed motor control(Ejection) H
31 R02 OUT Head feed motor control(Changing red and black ribbons) H
32 R03 OUT Head feed motor control(Head feed) H
33 R10 IN red or black ribbons control L
34 R11/EVND No use
35 R12/BUZZ OUT Piezoelectric buzzer control
36 R13 OUT Printer head pin1 H
37 R20 OUT Printer head pin2 H
38 R21 OUT Printer head pin3 H
39 R22 OUT Printer head pin4 H
40 R23 OUT Printer head pin5 H
41 R30 OUT Printer head pin6 H
42 R31 OUT Printer head pin7 H
43 R32 OUT Printer head pin8 H
44 R33 OUT Printer head pin9 H
45~48 R40~R43 OUT Step motor control
49~51 R50~R52 OUT Six LED SEG control H
52 R53 OUT Clock sensor control H
53~55 R60~R62 IN Six key and jumper wire control L
56 R63 IN Clock sensor input H
57~72 SEG17~SEG32 OUT LCD display SEG
73~76 COM1~COM4 OUT LCD display COM