Date: Wed, 11 Dec 1996 23:55:24 -0500 (EST)
From: Michael Phelps <morphine AT hops DOT cs DOT jhu DOT edu>
To: Eli Zaretskii <eliz AT is DOT elta DOT co DOT il>
cc: hars AT dutch DOT nl, djgpp AT delorie DOT com
Subject: Re: DOS/BIOS direct Floppy access
In-Reply-To: <Pine.SUN.3.91.961211171511.9242B-100000@is>
Message-ID: <Pine.GSO.3.95.961211235246.1003A-100000@hops.cs.jhu.edu>
MIME-Version: 1.0
Content-Type: TEXT/PLAIN; charset=US-ASCII


On Wed, 11 Dec 1996, Eli Zaretskii wrote:

> 
> On 10 Dec 1996 hars AT dutch DOT nl wrote:
> 
> >   registers.h.dh = test_drive ; // drive 0x00=A 0x01=B
>                 ^^
> Check your references.  This should be DL, not DH.
> 
> >   registers.x.ss = registers.x.sp = 0 ;
> 
> You should also zero out the registers.x.flags field.  If you don't, it 
> will work most of the time, but bite you one day.  (Btw, it's best to use 
> the `__dpmi_int' library function which does all this zeroing for you.) 
> 
> I also recommend to reset the drive (Int 13h/AH=0) after every 
> unsuccessful call to function 02h, as some drives will report bad status 
> forever and ever if you don't reset them.
> 
Thanks for catching the error.  This is a documentation error for the disk
access portion of the DJGPP Book project
(http://www2.ari.net/flyboy/filedisk.txt).  I will get around to
correcting and modernizing it.

						---Michael Phelps
						   morphine AT cs DOT jhu DOT edu


                               CH3
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                               N
                             / |
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                    /      \   CH2
             _____/         \__|__      
           //     \\        /  |  \\     
         //        \\______/___CH2 \\  
          \        /       \       /
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          / ------ \       /      \
        OH           \   /         OH
                       O
 
                   Morphine