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From: peterk@cbmger.UUCP (Peter Kittel GERMANY)
Newsgroups: comp.sys.amiga
Subject: Re: Blowing up your 1950
Message-ID: <606@cbmger.UUCP>
Date: 3 Dec 90 10:24:59 GMT
References: <964.2754A82B@weyr.FIDONET.ORG> <36456@cup.portal.com>
Reply-To: peterk@cbmger.UUCP (Peter Kittel GERMANY)
Organization: Commodore Bueromaschinen GmbH, West Germany
Lines: 24

In article <36456@cup.portal.com> thad@cup.portal.com (Thad P Floryan) writes:
>David.Plummer@f70.n140.z1.FIDONET.ORG (David Plummer)
>in <964.2754A82B@weyr.FIDONET.ORG> writes:
> 
>	[...]
>	Point being, nothing can instantly destroy your monitor.  Even if you
>	could damage it, I don't think anything could be so severe as to do
>	damage before you could turn it off.
>
>On the early IBM-PCs (and maybe still for all I know about "those" systems),
>it was possible to change video attributes by altering the values written to
>the registers in the video controller chip.  An errant program (or a malicious
>Trojan Horse) could also change the value in the register all the way down to
>ZERO.  Just imagine what used to happen when, say, an expected 15KHz AC signal
>on the CRT coil(s) is now pure DC.  Yes, it WOULD and DID destroy the CRT.

Yes, and you know why? Because PCs use the same 6845/6545 video controller
chip as in the SuperPET (or also 8032) mentioned in the original posting!
This 6845 appears also today as subset in the registers of every PC video
card. Was a quite useful part.

-- 
Best regards, Dr. Peter Kittel  // E-Mail to  \\  Only my personal opinions... 
Commodore Frankfurt, Germany  \X/ {uunet|pyramid|rutgers}!cbmvax!cbmger!peterk