Cpu; Cpu Signal Description - Sharp PC-1246 Service Manual

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Pin Signal
In/Out
Function standby= power off
No. name
1 V1
In LCD driving power
2 V2 In LCD driving power
3 V3 In
LCD driving Power
4 V4 In LCD driving Power
5 V5 Out
Expansion RAM chip enable, normally high, (Not used with the PC-1246.)
6 VDD Out LCD drive power, high during standby.
7 GND In Power supply
8 VGG In Power supply, normally low
9 X1 Out System clock oscillation output
10 X2 In System clock oscillation input
11 X3 Out
Display clock oscillation output
12 X4 In
Display clock oscillation input
13 K1 In
Key input, normally low
14 K2 In
Key input, normally low
15 K3 In
Key input, normally low
16 K4 In
Key input, normally low
17 K5 Out (SEL2) Select signal output
18 K6
Out (SEL 1) Select signal output
19 K7
In ACK signal. Enables the 1/0 (PCU) to read data from the CPU.
20 KB In
Data in. Serial data input from the PCU (bit-to-bit serial handshake)
21 RESET
In
Reset input, normally pulled down to low level. Reset when high.
22 Cl In
Option cassette tape recorder interface input
23
co
Out Option cassette tape recorder interface signal/buzzer signal output
24
R/W
Out Write clock, normally high
25 DI01 In/Out
Data bus, normally low
I I
2 2
32
DIOB In/Out Data bus, normally low
33 B1 Out
Address bus, low during standby. Also, used for peripheral data output port (Dout).
2
2
2
2
43
B11 Out
Address bus, low during standby. Also, used for peripheral data output port (Dout).
44 B12 Out
Basic RAM chip enable
45 B13 Out
Busy interface output port
46 S40
Out
LCD segment signal/key strobe, low or high during standby and 4-level pulse during display.
2 '
2
I
2
85 S1 Out
LCD segment signal/key strobe, low or high during stnadby and 4-level pulse during display.
86 H16 Out
LCD backplate signal, low or high during standby and 4-level pulse during display.
2 2 2 2
100
H1 Out
LCD backplate signal, low or high during standby and 4-level pulse during display.
• CPU signal description
A 100-pin, 4-bit, microprocessor used in this model has a 17KB ROM and display chip within the chip. What it differs from the
conventional microprocessor is that it has no iternal RAM but uses an external RAM for execution.
4.CPU(SC61720D03)
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PC-1246
PC-1247