[Coco] collecting info for converter

Gene Heskett gene.heskett at verizon.net
Wed Feb 8 17:14:23 EST 2006

On Wednesday 08 February 2006 05:43, Bob Devries wrote:
>on further investigation, it appears that the BBC Micro has TTL
> (digital) RGB output, which probably go 0-5V. I don't believe they
> use the RGBI, but just RGB and V & H Sync.

If its truely TTL, it should go from 100 to 600 millivots at black, and 
up 2.5-3.0 volts for peak britness.  The output stage has great pullups 
if it makes it to +4 volts unless its a heavy cmos driver.

>Will this present a problem? Will a resistor voltage divider be
> sufficiant to make this into the 0 - 0.7V required for Analog RGB?

Actually, on my coco3 there is a dc offset of about +600 millivolts that 
we had to compensate for.  Its been so long since I looked at an amiga 
that I don't recall the actual voltage range it outputs.


Cheers, Gene
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