> > I hadn't realized that on a PC w/ CGA that the light pen was getting
> > help from the CRT controller. That explains how a relatively simple
>
> Yes. On most machines designed to have light pens, the CRT controller
> does some of the work. The popular 6845, as I mentioned, has a lightpen
> input pin. Incidentally, both the BBC Micro and the Sirius/Victor9000
The Commodore VIC-II also supports light pens in hardware. When the switch is
closed, the light pen registers in the chip latch at the current raster
position if light is present and an IRQ is generated. (In simplistic terms.
*grin*)
--
----------------------------- personal page: http://www.armory.com/~spectre/ --
Cameron Kaiser, Point Loma Nazarene University * ckaiser_at_stockholm.ptloma.edu
-- This message will self-destruct in five seconds. Good luck, Jim. -- M:I ----
Received on Mon Jul 16 2001 - 13:32:01 BST