Re: Please Help me Somebody with DEMUX Gate

Posted by WBahn on Jun 18, 2019; 9:01pm
URL: http://nand2tetris-questions-and-answers-forum.52.s1.nabble.com/Please-Help-me-Somebody-with-DEMUX-Gate-tp4033175p4033312.html

michael1978 wrote

HI

THANK YOU
no no is for black and white

so it means i have to build DAC(simple like you say resistor devider) right?

It's been about 20 years since I played with direct VGA generation, but IIRC the sync signals are intended for 5 V TTL logic but should work with 3.3 V logic as long as you get above 2.7 V.

The RGB signals are from 0 V to 0.7 V, so for monochrome just use a diode and a suitable resistor to get those levels.

I seem to recall that to work with some monitors you had to embed the sync signals in the green channel. But I suspect that you probably don't for most monitors with the D-shell VGA connector (could be wrong).