Re: CRT gun driver levels?

On Fri, 21 Aug 1998 13:35:18 -0700, Clay Cowgill <ClayC@diamondmm.com> wrote:

>Al suggested a latch and a PROM to act as an intensity-look-up table.
>That could work-- bank switch the PROM depending on what game is
>selected for "N" intensity resolution... Could probably even have it
>handle the "two-level" intensity. My idea was KISS since I think Mark
>is still planning on something more complex. I'm more along the lines
>of cheap-easy-get-it-done since I'm long on projects and low on time.

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.

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.

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.

-Zonn

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Received on Fri Aug 21 17:09:10 1998