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2-3 Timing Chart
This section of the service manual describes the timing that the computer industry recognizes as standard
for computer-generated video signals.
Mode
IBM
VGA2/70 Hz
VGA3/60 Hz
720 x 400
640 x 480
Timing
fH (kHz)
31.469
A µsec
31.778
B µsec
3.813
C µsec
1.907
D µsec
25.422
0.636
E µsec
fV (Hz)
59.940
16.683
O msec
P msec
0.064
1.048
Q msec
R msec
15.253
0.318
S msec
Clock
Frequency
25.175
(MHz)
Polarity
Negative
H.Sync
V.Sync
Negative
Separate
Remark
Separate Sync
Horizontal
Video
Video
C
D
E
C
D
E
Sync
Sync
Sync
B
B
A
A
A : Line time total
C : Back porch
E : Front porch
AP17K*/AP17J*
Table 2-1. Timing Chart
640/75 Hz
640/85 Hz
640 x 480
640 x 480
(AP17K* Only)
31.469
37.500
43.269
31.777
26.667
23.111
3.813
2.032
1.907
3.810
25.422
20.317
17.778
0.636
0.508
70.087
75.000
85.008
14.268
13.333
11.764
0.064
0.080
1.080
0.427
12.711
12.800
11.093
0.413
0.027
28.322
31.500
36.000
Negative
Negative
Negative
Positive
Negative
Negative
Separate
Separate
Separate
Vertical
Video
Video
Q
R
Q
R
S
Sync
Sync
Sync
P
P
P
O
O
O
B : Horizontal sync width
D : Active time
VESA
800/75 Hz
800/85 Hz
800 x 600
800 x 600
53.674
46.875
21.333
18.631
1.556
1.138
1.616
2.222
3.232
2.702
14.222
16.162
1.556
0.323
0.569
85.061
75.000
13.333
11.756
0.671
0.056
0.064
0.578
0.503
0.448
11.179
12.800
0.023
0.019
0.021
49.500
56.250
Positive
Positive
Positive
Positive
Separate
Separate
S
O : Frame time total
Q : Back porch
S : Front porch
2 Product Specifications
1280/75 Hz
1024/75 Hz
1024/85 Hz
1280 x 1024
1024 x 768
1024 x 768
(AP17J*)
60.023
68.677
16.660
14.561
1.219
1.016
2.235
2.201
13.003
10.836
0.203
0.508
75.029
84.997
13.328
11.765
0.050
0.044
0.466
0.524
12.795
11.183
0.017
0.015
78.750
94.500
Positive
Positive
Positive
Positive
Positive
Positive
Separate
Separate
Separate
P : Vertical sync width
R : Active time
79.976
12.504
1.067
1.837
9.481
0.119
75.025
13.329
0.038
0.475
12.804
0.013
135.000
2-3
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