Vector (arcade) monitor interfacing issues

[Tom Jennings]

On Thu, 7 Oct 2004, Bob Shannon wrote:

> Is anyone on the list familiar with vector display monitors?

Not specifically, but related:


> I read 'The Secret Life of Vector Generators", and notices that Atari vector
> generators 'rest' the beam at the center of the screen.  There is a comment
> about
> doing this to prevent the deflection amp transistors from smoking.
> 
> But the HP 1350 graphics translator 'rests' the beam at the lower left hand
> corner of the screen, not the center.  

If the generator turns off write current (eg. Z axis off) when
"at rest" you can let the beam rest whereever you want. If it's
a 4-quadrant system eg. location (0, 0) is X=0V, Y=0V, you can
simply multiply X and Y by 0 when Z=0, aka turn off X and Y.

If you're simultaneously translating from 4-quadrant to
1-quadrant (eg. (0, 0) is X=0V, Y=0V) then you can force X=Y=
(fullscale / 2) whenever Z is off. 

Both schemes could be done with an opamp each dimension,
probably re-use one already present.