esc@hpcvlx.cv.hp.com (Ted S. Cline) (02/12/90)
I am eager to program the HP Vectra's HP D1180A VGA (Paradise) card's registers
to match NTSC (= VCR video input) timing. I hope you can help me.
I have a copy of the "HP D1180A Video Graphics Adapter Technical Reference
Manual" (HP D1180-90003, 10/89), but the timing registers remain a interrelated
puzzle to me.
I want to transfer animations (made with images from the public domain QRT
ray tracer) to my home VHS VCR. This would allow me to lengthen my short
(~6 second) animations by stringing several animations together. I am even
prepared to tape the video one image (= several video frames?) at a time.
If the pixel mapping is not changed, this would also allow using color TVs
as "VGA" monitors!
I have seen a working CGA-to-NTSC circuit (using a Motorola MC1377, as
described in Radio-Electronics Magazine, December 1989, page 81, complete kit
available for $29.95). But this only gives 320x200 x 4 colors, non-interlaced,
-not very exciting when compared to 640x400 x 256 color ray tracing images
seen on a VGA monitor.
The VGA card gives the V-sync, H-sync and analog R, G, and B signals that I
need (some amplitude reduction may be needed), but the timing is wrong.
I believe the first goal should be 640x200 x 256 colors, non-interlaced.
That would be great. The last step is to get the interlacing (may not be
attainable without card-external delay circuitry - unless you come to the
rescue!) to achieve 640x400 x 256 colors, interlaced. These resolution
numbers may have to be changed to fit the NTSC timing.
From a friend's copy of "Raster Graphics Handbook" by the Conrac Corporation, I
read on page 211 the USA broadcast NTSC timing:
Lines/Frame 525 <---------- half of this for non-interlaced ?
Field Rate 60 Hz
V-Interval 16,667 usec
V Blanking 833 usec
V-Sync Pulse 190.5 usec
H-Interval 63.5 usec
H Blanking 11.4 usec
H-Sync Pulse 5.1 usec
I have the ability to remap the image pixels if that becomes necessary. The
computer's VGA monitor need not be attached.
My initial hope is that _someone_ has approached this problem before and has
the solution already, or that someone can solve the register programming with
what little info I have supplied. And if neither, then please tell me what
information you need and I will provide.
I guess that commented assembly or C code would be the ideal response, but
I'd appreciate any comments.
Ted Cline CWO R&D Lab
esc@hpcvlx.HP.COM Hewlett-Packard, 4U-J8
[ihnp4|hplabs]!hpcvlx!esc 1000 NE Circle Boulevard
(503) 750-4064 Corvallis, OR 97330 USA