Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!brutus.cs.uiuc.edu!wuarchive!swbatl!texbell!vector!attctc!chasm
From: chasm@attctc.Dallas.TX.US (Charles Marslett)
Newsgroups: comp.os.minix
Subject: Re: Device drivers damaging HW
Summary: IBM Mono monitor is the most likely culprit
Message-ID: <8803@attctc.Dallas.TX.US>
Date: 29 Jul 89 15:47:41 GMT
References: <13679@ea.ecn.purdue.edu>
Organization: The Unix(R) Connection, Dallas, Texas
Lines: 45

In article <13679@ea.ecn.purdue.edu>, jel@ea.ecn.purdue.edu (Jim Lumpp) writes:
> I am not very familiar with IBM peripheral hardware and was 
> told it is possible that the drives and monitor of a PC could 
> be damaged by incorrectly written device drivers (i.e., by 
> having students write them).  Is this true?  How susceptible 
> is the IBM hardware to such damage?

The color monitors shipped by IBM and all (virtually all?) their clone-ers
are very robust in this respect -- I regularly set up the screen and leave
it in very abnormal timing configurations including the most dangerous one
of leaving off the sync signals completely -- this is a "synchronous" or
"asynchronous" reset of the EGA or VGA chip.  I have been told that this was
once a problem with the Seiko 1430 monitor, but it has since been fixed -- I
have one that came into the country many months before they started
selling them retail, and it has the protection circuitry, so this problem
must have shown up only in Japan (?).

On the other hand, the IBM digital monochrome monitor (50 Hz refresh, trails,
ugly, ...) does not have any protection circuitry, so it can distroy itself
if driven to a horizontal frequency far off from its normal value.  A reset
will not cause a problem though, because it drifts to its normal frequencies.
[This is the source of the warning from Hercules that the configuration of the
6845 should always be done in assembly language -- if done in Basic, you could
have an error and rewrite only a subset of the registers, pop back into
command mode, and wipe out your monitor.

In any case, you should have many seconds before any real damage is done, so
a careful student should be prepared to turn off the monitor (or computer) if
the screen breaks up or goes blank if he has a monitor that is susceptible
to such damage.

> thanks in advance,
> Jim Lumpp
> 
> internet: jel@ecn.purdue.edu   
> uucp:     ...!{decwrl,gatech,ucbvax}!pur-ee!jel


Hope this helps,
Charles
===========================================================================
Charles Marslett
STB Systems, Inc.  <== Apply all standard disclaimers
Wordmark Systems   <== No disclaimers required -- that's just me
chasm@attctc.dallas.tx.us