23 Aug
2018
23 Aug
'18
9:06 p.m.
On 08/23/2018 08:31 PM, Eric Schlaepfer via cctalk wrote:
I'm not that lucky! But yes, an early card with
the light pen connector
should work.
The card I used for the demo is a somewhat later revision. I added rework
wires to match the schematic in the technical reference manual of the
earlier revision.
I had the original MDA and a rather ancient light pen from some graphics
console or another. I hooked it up to a 6-pin Berg header and got it to
work, sort of. I didn't use the interrupt 10h BIOS functions, though,
but rather accessed the 6845 registers directly.
The operation was pretty terrible. The medium-long persistence of the
monochrome monitor led to large positioning errors.
I recently sent the pen to Glitch, who hasn't gotten back to me to
report wether it still works. It was pretty nice with a
pressure-activated tip swich with fiber optics coupled to a
phototransistor, with a couple of transistors to boost the signal.
Black with a coiled cord--6 conductors, I think.
--Chuck