RE: CRT gun driver levels?

> The PROM idea should work great. You won't need to run the beam
> On/Off line
> through it since it is handled the same by all platforms.
>
I'm not following the "run the beam On/Off line through" part. You
still need beam on/off for blanking control right? If the lookup PROM
is big enough you could run "on/off" to an output enable (with
pullups/downs on the outputs) or to a high address line on the PROM so
that when "off" is asserted the PROM always outputs "00" or something
(aka, color guns off) for intensity, no?

> The other cool thing about a PROM as a intensity-look-up is that you
> could
> easily convert the two color games to shades of gray. That would be
> pretty
> cool.
>
Oh, yeah. That would be neat...

> The formula for RGB to gray scale that takes into account the fact
> that our eyes
> are more sensitive to green, etc is:
>
> gray_value = R * 0.2989 + G * 0.5870 + B * 0.1140
>
> It should be pretty easy to adjust the PROM lookup for color to
> convert it to
> gray scales.
>
Gotcha... So it takes roughly twice as much brightness of a pure red to
equal the perceived brightness of a pure green? Guess I remember that
 from comp-graphics school... Been a while since I've worried about
conevrting stuff to grayscale though! ;-)

-Clay
Received on Fri Aug 21 17:56:18 1998