-2-
Pin Signal
In
/
Out Function
standby=
power
off
No. name
1
V1 In LCD
driv
i
ng power
2
V2 In LCD driving power
3 V3 In LCD driving Power
4 V4 In LCD
d
r
iving Power
5
V5 Out
E
x
pansion RAM chip
enable
,
normally high, (Not used
w
i
th 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
D
i
splay 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
s
i
gnal. 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
I
n
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
periphe
r
al
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
d
i
splay.
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
s
i
gnal
,
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
descr
i
ption
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
i
t
has
no iternal RAM but
uses
an external RAM
for
execut
i
on.
4.CPU(SC61720D03)
-
PC-1246
PC-1247
