Light pens?

[Jim Leonard]

Cameron Kaiser wrote:
> The VIC-II knows at any given point in time which pixel coordinate the
> raster beam is currently at. Within the light pen is a sensor which can
> pick up the presence of the beam. 

Does that mean the screen must be non-black for a light pen to work?
-- 
Jim Leonard (trixter at oldskool.org)                    http://www.oldskool.org/
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