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From: robert@hemingway.WEITEK.COM (Robert Plamondon)
Newsgroups: comp.sys.ibm.pc
Subject: Re: Disk Driver Formatting in
Message-ID: <799@hemingway.WEITEK.COM>
Date: 29 Sep 89 20:00:22 GMT
References: <89090607413782@masnet.uucp> <14789@netnews.upenn.edu>
Reply-To: robert@hemingway.WEITEK.COM (Robert Plamondon)
Organization: WEITEK, Sunnyvale CA
Lines: 25

>>    I have a 3.5 " disk drive that can read 720K and 1.44M diskettes. It
>>is installed as the drive A: on my system. When I start the system, the 
>>first diskette I read in this drive via aDIR command will have the 
>>proper directory, but any other diskette read later will give me the 
>>SAME directory as the first one, even if it's another. It seems that DOS
>>cannot re-read the FAT and DIR sectors. The diskettes I tried are both 
>>formatted in DOS 3.3 and DOS 4.01. . . . .

DOS (or the BIOS) expects the diskette drives to have a "READY" signal
that indicates whether the diskette has been replaced.  If it expects
this signal from a drive that doesn't provide it, it thinks that it
still has the original disk in its drive, and uses the copy of the
directory and FAT in RAM, rather than reading it from the floppy
again.

Typing control-C will cause it to flush these buffers, at least in
DOS 3.3.

A different BIOS or an installable device driver will probably fix
the problem.

	-- Robert
-- 
    Robert Plamondon
    robert@weitek.COM
    "No Toon can resist the old 'Shave and a Hair-Cut'"