1 Feb
2008
1 Feb
'08
midnight
Date: Thu, 31 Jan 2008 23:04:55 +0000 (GMT)
From: Tony
IIRC, while the MDA card had a light pen connector, it
was never really
documented or supported by IBM, due to the fact that light pens didn't
work properly with the very long persisnence phosphor of the 5151
monitor. The CGA card's light pen connector was docuemtned, though
(although I have never seen a light pen designed to work with it
I've got a light pen that was salvaged from some 60's era graphics
equipment. This is the kind with the fiber optic tip and a
microswitch that determines when the tip is depressed. Has some
discrete circuitry in it (probably an amplifier, pulse shaper, etc.)
and works just fine with the MDA/CGA/EGA cards. About the diameter
of a felt tip marker (ca. 3/4"). I once used it with a monitor with
a short-persistance white phosphor. It wasn't bad; just couldn't
think of a good application for it. I've got a VGA card here
(Paradise I think) that also has the connector, but it's hooked to an
LCD monitor, so that's not going to work very well--but does give
another reason to hang onto CRT displays.
Cheers,
Chuck