Xref:	news2.mv.net comp.os.msdos.djgpp:1220 comp.os.msdos.programmer:20878 comp.sys.ibm.pc.hardware.storage:43950
Newsgroups:	comp.sys.ibm.pc.hardware.storage,comp.os.msdos.programmer,comp.os.msdos.djgpp
From:	kaikow AT standards DOT com
Subject:	_bios_disk using C to read a logical drive's sectors
Originator:	kaikow AT mv DOT mv DOT com
Message-ID:	<DMz38A.1Hp@mv.mv.com>
Sender:	kaikow AT standards DOT com
Reply-To:	kaikow AT standards DOT com
Organization:	MV Communications, Inc.
Date:	Sun, 18 Feb 1996 13:09:46 GMT
Followup-To:	poster
Lines:	25
To:	djgpp AT delorie DOT com
DJ-Gateway:	from newsgroup comp.os.msdos.djgpp

I am having trouble finding "documentation" of how to read sectors from 
logical drives. It appears that I am not the only one having such 
problems, as I have found one shareware and one freeware disk editor that 
produce differing results. Alas, neither editor is in source form, so I 
am unable to see what they are doing.

Using the DEBUG command, I can see sector 0 on each logical drive 
(altough I have not yet tried that with the CD-ROM drive).

In addition, the DJGPP port of GNU C has a biostest.c program that has 
the same difficulty I am seeing. Both my program and biostest.c read the 
correct sector 0 from floppies but not from hard drives (yes, I am using 
0x80, etc. for the hard drives).

KB article Q39311 does clarify one issue, i.e., _bios_disk only accesses 
physical devices, not logical drives on a device, so that would explain 
why logical drive e: is not handled correctly. I guess that I have to 
grab a partition table somewhere to get drive e:'s sectors.

Is there source code available to demonstrate how to read a sector from 
any logical drive? Somewhee on the vast WWW, there is likely source for a 
disk editor, guess that I'll start looking.

The solution could be distributed with DJGPP.

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