Pin Function - Casio fx-9750G Operation, Service Manual & Parts List

7. PIN FUNCTION

CPU HCD62121A03 (HC-3017): COB
NOTE: The CPU is bonding on the PCB. If the CPU is defective, replace the PCB ass'y because
the CPU cannot be replaced.
Pin No. Pin Name
1 ~ 14 KO14 ~ KO1
15 ~ 22 KI8 ~ KI1
23 BUFON
24
25
26 ~ 46 AO20 ~ AO0
47 ~ 54 IO0 ~ IO7
55 OEBO
56 WEBO
64 CS3BO
69 ~ 72 OPT3 ~ OPT0
73 PORT7
74 PORT6
75 PORT5
76 PORT4
80 PORT0
81 VSS
82
83
84 VDD
85
86
87 VCC
88 VREG2
89, 90 TS1, TS2
91 VSSR
94 VSS
96 ITOFF
97 TEMU
98
99 VDB
100 VREG1
101 VREG4
102 VREG5
103 VDT1I
104 VDT2I
105 VREG3
Input/Output
O
I
O
IT2 I
IT0 I
O
I / O
O
O
O
O
I
I
O
O
I
I
PI I
PO O
I
XO O
XI I
I
O
—
I
I
I
—
SW I
I
—
O
—
I
I
—
Function
Key common signal
Key input signal
Chip select for RAM
Interrupt input
Interrupt input
Address bus
Data bus
Output enable signal for RAM
Write enable signal for RAM
Chip selecting signals
Changeover signal
Receiving terminal for data communication
Receiving terminal for data communication
Transmitting terminal for data communication
Transmitting terminal for data communication
Low battery message for back-up battery (2.6 V)
GND
4.3 MHz clock input
4.3 MHz clock output
+6 V source
Clock output
Clock input
+6 V source
Voltage for main switch detection
Test terminals of factory purpose only
GND
GND
Switching terminal from main switch
Test terminals of factory purpose only
Receiving terminal for reset switch
+3 V source
Test terminals of factory purpose only
+3 V source for ROM
Test terminals of factory purpose only
Forced power off detecting terminal (2.3 V)
Low battery message for main battery (2.5 V)
+3 V source for RAM
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