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From: mjg@ecsvax.UUCP
Newsgroups: comp.sys.ibm.pc
Subject: Re: Is your disk drive REALLY compatible ?
Message-ID: <2884@ecsvax.UUCP>
Date: Wed, 8-Apr-87 09:15:46 EST
Article-I.D.: ecsvax.2884
Posted: Wed Apr  8 09:15:46 1987
Date-Received: Sat, 11-Apr-87 07:27:53 EST
References: <2856@ecsvax.UUCP>
Organization: UNC Educational Computing Service
Lines: 27
Summary: AT 1.2 Meg drives must use 1.2 Meg disk

I posted an article April 3 the essence of which was:
> 	Anyone who uses a program that accesses floppy disk drives
> in a non standard fashion should be aware of the following compatibility
> problem. Some drives are definitely too clever for their own good and
> can affect the proper working of programs like Fastback.
> 
I suggested the following test:
> 
> Take a regular PC or MS-DOS disk and put it in the drive under test. Type DIR
> and see what you get. Then take the same disk and cover the index hole with
> an OPAQUE sticker such as a write protect tab. Type DIR and if you get the
> same as before then all is well (You see, the PC does NOT rely on the index
> hole for reading and writing - only for formatting). If you get an error
> message then your drive is one of the bad guys. It may be possible to fix
> it by changing jumper settings. In any case I would appreciate hearing from
 anyone that tries the test so that I can compile a list of good and
 bad which I will the post to the net.

It has been pointed out that this test fails if you use a 360k disk
in a 1.2 Meg drive. The reason is that the BIOS looks first to see
if the disk is a 1.2 Meg type and, since there is no index hole,
it never gets beyond this point but just hangs. To check your HD
drives use a 1.2 Meg formatted disk.

As before send results to me,

Mike Gingell ....decvax!mcnc!ecsvax!mjg