C.P.UBLOCK DIAGRAM AND PIN ASSIGNMENT<PORTLIST>74HD404889
port Name Function Description Logic
2 R70/AN0 IN NiCd batterychange controlsignal
3 R71 IN Mechanical switches L
4 R72 IN Red/Blackribbon check switch L
5 R73 IN Head positioncheck sensor(E-30) L
6 R80 IN Card right/back side checksensor H
7 R81 IN Card right/back side checksensor H
17 D0/INT0 IN Headfeed encoder sensor input(E-38)
18 D1/INT1 IN Paperfeed encoder sensor input(E-37)
19 D2 OUT H
20 D3 OUT Five sensorscontrol H
21 D4 IN AC Failure detection signal H
22 D5 IN 5V monitoring H
23 D6 OUT Timesignal control H
24~26 D7~D9 OUT Six key and jumper wire scan control L
27~28 D10~D11 OUT SixLED 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(Changingred and black ribbons) H
32 R03 OUT Head feed motor control(Head feed) H
33 R10 IN red orblack 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 Sixkey and jumper wire control L
56 R63 IN Clock sensorinput H
57~72 SEG17~SEG32 OUT LCD display SEG
73~76 COM1~COM4 OUT LCDdisplay COM