computer graphics in the 1950s
ard at p850ug1.demon.co.uk
Sat Oct 18 14:51:50 CDT 2008
> > There was a color vector display technology that didn't use a shadow
> > mask or phosphor dots, but it was very uncommon. It used two layers of
> > phosphor with different activation energies, and the high-voltage supply
> > was actually switched between two voltages. The lower voltage only
> > activated one phosphor, but the higer voltage activated both, so two
> > different colors were available. This was used in the DEC VR20 monitor,
> > of which few units were believed to have been sold.
> I haev an HP1350 'graphics translator' here -- it's an HPIB input vector
> display generator. The manual mentions an HP colour vector monitor for
> this unit, which would appear to work as you described, alas I've never
> seen one (I have the HP1311 monochrome monitor only). I cna dig out the
> model number if anyone wants to look for one.
I have looked in the HP1350 manual, the monitor in question is the
HP1338. I can find no mention of it on the web at all, alas.
According to the HP1350 manual, it had a 2-bit colour selection input,
providing 3 colours (the 4th state repeated one of the other colours).
Said colours were red, yellow, and green. I have no idea how it worked,
whether it was a shaddowmask CRT (but if it was, why not also have blue?)
or one with difference energy phosphors.
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