Sharp PC-4741 Service Manual page 22

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ress
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80 X 25 taxt
-
P C-4741
eGA (A
JT)
mode A TT mode
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40 X 25 text 80 X 25 text
--
640 X 400
Graphics
Fig_ 3-20 Display buffer memory allocation
3-17-2-1_ Text mode
80 x 25 text (MDA)
• 80 x 25 text (CGAlATT)
• 40 x 25 text (CGAlATT)
The LCD control circuit supports the text 80 x 25 MDA alphanumeric
mode and 80 x 25/40 x 25 CGAlATT alphanumeric mode.
Every character to be displayed has one byte of character code with
one byte of attribute. The attribute has four functions described next.
Background Foreground
Display mode
R
G B R G B
0 0
0
0
0 0
Non display
0 0
0 0 0 1 With underline
0
0 1 1 1 1
Normal display
1 1
1
0
0 0
Reverse display
7
6
5
4 3
2
0
I
Character Code (Even Address)
I
BL
I
R G B R G B Attribute Code (Odd Address)
T
Foreground
I
T
Intensity
Background
Blink
fig,
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-21-
V-RAM
1
213 14 15 16 17 18 ~- ..... - . " "
81 160
t;-;;
0
T
~----
...
-
...
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..
--.--
..
-----.-
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Fig. 3-22 VRAM map in the 80 x 25 text mode (MDA)
1
213 14 1
5
16 17 la
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~ ~
V-RAM
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4
00000
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8
1998 1999 2000
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Fig. 3-23 V-RAM map in the 80 x 25 text mode (ATT)