Horizonal Timing
Horizonal Dots 640 640 640 VgaGen
Vertical Scan Lines 350 400 480 100608
Horiz. Sync Polarity POS NEG NEG -
A (µs) 31.77 31.77 31.77 Scanline time 32
B (µs) 3.77 3.77 3.77 Sync pulse length 3.85
C (µs) 1.89 1.89 1.89 Back porch 1.9
D (µs) 25.17 25.17 25.17 Active video time 25.6
E (µs) 0.94 0.94 0.94 Front porch 0.65
(MHz) 25.175 25.175 25.175 Pixel Clock 25.000
800 800 800 Total “pixels” 800
______________________ ________
________| VIDEO |________| VIDEO (next line)
|-C-|----------D-----------|-E-|
__ ______________________________ ___________
|_| |_|
|B|
|---------------A----------------|
Vertical Timing
Vert. Sync Polarity NEG POS NEG -
Vertical Frequency 70Hz 70Hz 60Hz 59.52
O (ms) 14.27 14.27 16.68 Total frame time 16.8
P (ms) 0.06 0.06 0.06 Sync length 0.064
Q (ms) 1.88 1.08 1.02 Back porch 1.056
R (ms) 11.13 12.72 15.25 Active video time 15.36
S (ms) 1.2 0.41 0.35 Front porch 0.32
449 449 525 Scan Lines 525
______________________ ________
________| VIDEO |________| VIDEO (next frame)
|-Q-|----------R-----------|-S-|
__ ______________________________ ___________
|_| |_|
|P|
|---------------O----------------|
Informations source
* HP D1194A Super VGA Display & HP D1195A Erognomic Super VGA Display Installation Guide, Hewlett Packard
--------
"VGA industry standard" 640x480 pixel mode
General characteristics
Clock frequency 25.175 MHz
Line frequency 31469 Hz
Field frequency 59.94 Hz
One line
VgaGen clock ticks (20 MHz)
8 pixels front porch 13 (including right border)
96 pixels horizontal sync 77
40 pixels back porch 38 (including left border)
8 pixels left border -
640 pixels video 512
8 pixels right border -
---
800 pixels total per line 640
One field
2 lines front porch
2 lines vertical sync
25 lines back porch
8 lines top border
480 lines video
8 lines bottom border
---
525 lines total per field
Other details
Sync polarity: H negative, V negative
Scan type: non interlaced.
Information source
* Article "Re: VGA specifications ,where?" posted 19 Nov 1997 to sci.electronics.design newsgroup by Jeroen Stessen
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