Tandy 1400LT Service Manual page 208

5. Interface Specifications
5-1 Terminal Pin Assignment
I
#loo
#
1 .
# 2
Pin No. Symbol Function
1-4
5-8
9
10
11
12
13
14
15
16
17
18
19
20
UDO-UD3
LDO-LD3
vss
CP
LOAD
DF
FRAME
NC
VDD
vss
VEE
VEL 1
NC
VEL2
DATA input signal of upper screen (Fig A-4)
DATA input signal of lower screen (Fig A-4)
G N D
Shift register clock pulse for segment driver.
Signal for latching 1 line shift register DATA & common driver DATA shift signal.
A.C. signal for LCD driving
Start signal of each display cycle (Shift register DATA signal of common driver)
No connection
+5V (Supply voltage for logic circuit)
G N D
Supply voltage for LCD driving
Supply voltage for EL Back light
Supply voltage for EL Back light (GND)
No connection
5-2 Relationships of DATA input signal and LCD Screen division
#
#
1
2
.
( D l - w m o
C 3 c ) O c ) b
- ( V c ) b v ) ( D ( D ( D ( D ( D
n L 3 n n n
--------------------
n n n n n
1 1 1 1
t l K I
UDo+D4,D8,D12
. . .
.
D640
UD14D3, D7, D l l ,
.
. . .
D639
UD,+DZ, D6, D10,.
. . .
D638
UDj+Dl, D5, D9,
. . . .
D637
I
I
I
I
I
I
I
I
LDo+D4, D8,D12,
. . . .
D640
LDl+D3, D7, D11,
. . . .
0639
LDz-+D2, D6, D10,
. . . .
0638
LD3+D1, D5, D9,
. . . .
D637
Figure A-4. LCD Sreen
A-5