From: linnenba@cs.utwente.nl (George Linnenbank)
Subject: Re: diskette drive puzzle - help!    
Organization: University of Twente, Dept. of Computer Science
Date: Fri, 22 Jan 1993 09:49:00 GMT

In article <1993Jan20.213619.19025@kronos.arc.nasa.gov>, chguest@pioneer.arc.nasa.gov ( Charles J. Guest ) writes:
|> Okay folks I got one for you, how's this for an unusual problem:
|> 
|> Hardware: AMI 386
|> Floppy drive a: 1,2 meg 5.25 inch
|> Memory: 640+384  and 3 meg expanded on add in card.
|> DOS: 4.01
|> 
|> I had un unusual failure last night.  I would put a 5.25 inch
|> disk in drive a, do a 'dir' on it and get the information. I
|> then put a new diskette in it and did a 'dir' and got the SAME
|> information as on the first disk... problem was the diskettes
|> were totally different.  Even the serial numbers on the diskettes
|> showed the same.  This problem would go away with a power off
|> or a reboot, that is to say it would now read the second diskette okay,
|> but if I put in a third it would again show the same dir information
|> from diskette two.
|>  
|> It would access files from the first diskette okay, but if I put
|> in a new diskette and attempted to run a program known to be on
|> diskette 2, it would not find it, seemingly because it still thought
|> it had the first diskette in there.
|> 
|> The obvious question:  What the heck have I got broken here.
|> 
|> I checked for viruses with the new McAffee scan (99?) (97?) but
|> nothing was found.  I was told possibly a bad drive, but I cant
|> figure out how that would be the problem.  I am thinking controller
|> card, but that same card also controls my HD, so I dont want to 
|> mess with it if I dont have to.  I also am playing with the idea
|> that it is something funny on the motherboard.  Ugh. Yea it was
|> used, but an old QAplus checked it out okay before I installed it.
|> 
|> Any ideas?
|> 
|> Thank you. 
|> Charles
|> 
|> +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
|> + *READ* ---> The opinions expressed above are to the best of my knowledge, +
|> + however all options should be discussed with persons who have professional+
|> + training with the subjects covered here. * ALL POSSIBLE DISCLAIMERS APPLY!+
|> + ____FROM: chguest@pioneer.arc.nasa.gov =>or<= sun!ames!pioneer!chguest____+
|> +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
|> +  ...One useless man is called a disgrace, two are called a law firm, and  +
|> +     three or more become a congress....                                   +
|> + A new Soviet/American truism - KGB does NOT stand for Kinder Gentler Boys +
|> +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++


It seems to me a physical error. The disk drive doesn't detect a change of
diskette. But at start-up the current disk hasn't been read yet, therfore
it will be read. But when you change the disk and the disk drive doesn't 
detect that, it 'thinks' : "Ah, another access to the same disk. I still
have the data in a buffer. I don't need to access the diskette itself!"

To solve the problem I would suggest you to check the disk drive and the 
cable to the controller. Perhaps cleaning it from dust would already do
the job.

Hope it helps,

George.
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