[Simh] Improved CRT simulation

[Phil Budne]

Paul wrote:

> If you insist on round looking points, probably so.  But I find that
> a 1k wide emulated device on a "4k" display works fine.

Good to	know!  I was walking around today and realized anti-aliasing
surrounding 2x2 might do the trick!  Alas, I foolishly cheaped out on
the desktop all-in-one I'm typing this on, and didn't opt for a 4K display :-(

> Displays tended to be pretty dim to preserve the screen, and the basic look was roughly bitonal.

The DEC 340 has multiple brightness levels (as did the MIT modified
DEC Type 30 used to create Space War) and used tubes with two
phosphors, a quick blue-white fluorescence and a slow yellow-green
phosphorescence, so perhaps a different beast than the CDC display....

Alas, I've never seen a running PDP-1.  I worked in the building next
to the Bell's Computer Museum when it was in Marlborough, and it's
possible they may have demo'ed spacewar now and then.  They had TX-0,
which had been restored to running condition, but I didn't understand
its significance until much later.....

p