RGB-VGA Converter -- buy or build?
trixter at oldskool.org
Sat Mar 20 00:12:31 CDT 2010
On 3/17/2010 3:06 PM, Tony Duell wrote:
>> On 3/16/2010 3:09 PM, Tony Duell wrote:
>>> What are you really trying to do? Waht is the machine you are taking the
>>> outputs from, and what are you trying to do with them?
>> Trying to capture the output of a program running on an IBM 5160 that
>> only looks correct via CGA RGB output.
> Right. And what are you capturing it on? What inputs _exactly_ do you
> have? For example, do you have separate syncs, composite sync, or
I'm not sure I understand the question: There is no capture device made
that can do it, so I have no device to capture from.
I do have an Extron unit that can convert RGB TLL to analog RGBH with
sync on green but it doesn't handle the *I* of RGBI, nor the recoloring
of color index #6.
I have a solution that works for 95% of the cases that don't involve
timing tricks (like switching palettes mid-screen) that is cheating, but
it seems to work: I have an old ATI VGA with a program that can put the
card into a CGA-like mode where the register writes behave like CGA and
not like VGA -- palette and background changes work like they should on
CGA, the font is 8x8 like CGA, and the output is 400 lines (200
line-doubled) and that can be captured with any vga->video converter.
It's the last 5% I'm striving for, since the stuff worth capturing is
the stuff that uses tricks to extend CGA.
>> Had I enough free time, I could learn it too, but I don't have much
>> these days. My free time in my youth was spent learning the hardware
>> from the outside (ie. assembler programming), not the inside.
> I have the opposite problem. I learnt hardware first. Which means I tend
> to think about probramming as to what it will do to the hardware
> (somtimes at a very low level).
Ah, but then you would like assembler -- that's where our two worlds meet.
Jim Leonard (trixter at oldskool.org) http://www.oldskool.org/
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