computer graphics in the 1950s

[Tony Duell]

> That's true of many (but not all) the B&W vector games, such as 
> Battlezone and Red Baron, but not of the color vector games.  In the 
> color vector games, the CRT itself introduces pixelization, because of 
> the holes in the shadow mask and the discrete phosphor dots.  The 
> resolution isn't really all that great.

Did anyone try using 3 monochrome CRTs and combining the outputs 
optically (e.g. by back projectuion)? That would get round the need for a 
shadowmask 

(The reverse, splitting up the image into primary colours using dichroic 
prisms and imaging the result with 3 vidicon tubes, was not uncommon in 
colour video cameras at one time).

> 
> 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.

-tony