8 May
2005
8 May
'05
7:44 p.m.
On 5/8/05, Tony Duell <ard at p850ug1.demon.co.uk> wrote:
Aha! The famed HCF instruction? :?)
--
Liam Proven
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[...] if the
wrong value is entered,
it causes something dire to happen in the TV section's logic (eg, if the
horizontal frequency is too low then the flyback transformer's impedence
drops and draws a lot of current and smokes).
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....