RGB-VGA Converter -- buy or build?

[Jim Leonard]

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
> sync-on-green?

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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