Converting TTL monitor to Analog

From: Richard Erlacher <edick_at_idcomm.com>
Date: Thu May 10 10:10:11 2001

see below, plz

Dick
----- Original Message -----
From: "Chuck McManis" <cmcmanis_at_mcmanis.com>
To: <classiccmp_at_classiccmp.org>
Sent: Wednesday, May 09, 2001 1:29 PM
Subject: Re: Converting TTL monitor to Analog


<snip>
>
> Color monitors have a color mask, and that color mask has a 'dot pitch'
> which defines where you can display pixels. If you attempt to display more
> pixels on a line than there are holes in the mask, then you will get
> banding artifacts.
>
I've seen no evidence of this. If this were the case, then the fact that many
display systems use inexpensive 1000 ppm oscillators would cause enough
variation that it would be obvious on those monitors having this feature.
Moreover, horizontal phase adjustment and vertical height/horizontal width
adjustment would be impractical.
>
> Next there is frequency response. The amplifiers that connect to the color
> guns have something called a 'slew rate' which is the rate at which they
> can change their output color. If you put to many pixels side by side then
> you will start seeing color degradation due to the fact that the amplifier
> can't get to the new color fast enough. If you display several columns of
> vertical white lines on a black background you will see (in cheaper
> monitors) that the leading edge of the while line is not white, its gray.
> And as you increase the number of lines the white lines will get grayer and
> eventually you will have just a gray screen.
>
Amplifier bandwidth issues are a factor in the practical use range of a given
monitor. However, that has nothing to do with whether a monitor is analog or
digital in nature.
>
> You "can" drive monitors all over the map, eventually you will destroy them
> if you allow the horizontal output driver to over heat. However, getting an
> acceptable signal out of one is more constrained.
>
While that's true, it's hard to do.
>
> --Chuck
>
>
>
Received on Thu May 10 2001 - 10:10:11 BST