when I was in high school (teaching the grade 9 class, not taking it)
- one kid got to pay the repair bill on the Commodore PET.
One magic poke to the 6845, and PPPPFT! there goes the monitor cicuitry;)
But thwen again, random pokes to random locations will cause havoc...
The real (blue) screen of death! (monochrome 40 col. version)
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Liam wrote:
This is not as
rare as you might think. Several machines -- the IBM PC
MDA card + 5151 monitor, for exampe -- suffer from this. There is no
horizontal oscillator chip in the monitor circuit, the line output stage
(horizontal output stage) is driven from the signal produced by a
software-contorlled IC (in the case of the MDA card, it's a 6845).
Mis-programming that does just what you said....
Aha! The famed HCF instruction? :?)