Sharp PC-1211 Service Manual page 9

9
Fig 2-3-1
The numerica figure "4", to be displayed by the CPU II, is converted into the relevant character
code and carried through on the address data bus. First of
all,
the segment Sl is selected with the
address A8-Al "00000000" to store the data DI04-DI01 "1000"
in
the display buffer (see Fig.
2-3-1 ). To store second half 4 bits of the data, only AS in the address in turned "1" to make the
address "00010000" to store data "0001 ". In the same manner, the address "00000001" is selected
for storing the first half 4-bit data "O 100" for he segment S2 and the second half 4-bit data "000 I"
is stored with the address "00010001 ".
S40
S32
S33
S34
Sl6
Sl7
Sl8
1
S2
A5=0 A5=1
DI04 DI02 DI04 DI02
'--------..,..-~
Address
0
1
0 0 0
)
F
0
1
0 0 1
)
F
0
1
0 1 0
~
F
Al
I
A8 A7 A6 A4
Hl
DDD•D
H2
oo••o
H3
o•o•o
H4
•oo•o
H5
•••••
H6
ooo•o
H7
ooo•o
Sl S2 S3 S4 S5
Ex: Displaying numerical figure "4"
There are 8 x 40=320 bits ( 40 bytes)
of area in the display buffer in the
display chip.
Display buffer
XOOl 0100
H8 H7 H6 H5 H4 H3 H2 Hl
XOOl 1000
Counter/
decoder
HA
The contents of display indicated by the CPU I is received by the CPU II via the input buffer and
makes converted into respective character codes, then they are carried over to the display buffer in
the display chip through the address data bus.
• Designation of the display data
The following structure is observed in the display buffer in the display chip.
2-3. Display
the
ata.
'U I
up
fer,
.in
v
d