[COFF] Re: White Backgrounds on GUIs after Dark Backgrounds on Terminals?

[Paul Winalski <paul.winalski@gmail.com>]

On 6/15/23, segaloco via COFF <coff@tuhs.org> wrote:
>
> So terminals, they started as typewriters with extra steps, a white piece of
> paper on a reel being stamped with dark ink to provide feedback from the
> machine. When video terminals hit the market, the display was a black screen
> with white, orange, green, or whatever other color of phosphor they bothered
> to smear on the surface of the tube. Presumably this display style was
> chosen as on a CRT, you're only lighting phosphor where there is actually an
> image, unlike the LCD screens of today. So there was a complete contrast
> shift from dark letters on white paper to light letters on an otherwise
> unlit pane of glass.

The phosphors on CRT screens don't last forever.  You only want to
light them when necessary.  CRTs also suffer from the problem of
burn-in.  If you keep the same picture illuminated for a long period
of time that pixel pattern gets burned into the phosphors.  This is
why the later GUI CRTs had screen saver software that displayed an
ever-changing picture to prevent burn-in.  This isn't a problem with
the modern, non-cathode-ray displays.  Good ol' flying toasters.

-Paul W.