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From: dragheb@isis.UUCP (Darius "OPRDRT" Ragheb)
Newsgroups: comp.sys.ibm.pc
Subject: Re: number of DOS drives
Message-ID: <1450@isis.UUCP>
Date: Thu, 4-Dec-86 01:10:02 EST
Article-I.D.: isis.1450
Posted: Thu Dec  4 01:10:02 1986
Date-Received: Fri, 5-Dec-86 00:49:32 EST
References: <2268@sdcsvax.UCSD.EDU> <623@bucsb.bu.edu.UUCP>
Reply-To: dragheb@isis.UUCP (Darius "OPRDRT" Ragheb)
Organization: Math/CS, University of Denver
Lines: 41
Summary: Got it this time....I think :-)

In article <623@bucsb.bu.edu.UUCP> madd@bucsb.bu.edu.UUCP (Jim Frost) writes:
>>
>>In article <1441@isis.UUCP> dragheb@isis.UUCP (Darius "OPRDRT" Ragheb) writes:
>>>
>>>I think this might work (I have not tried it):
>>>use function (_FUNCTION_, not interrupt) call Eh. It will do two things:
>>>make the drive selected in DL the current drive, and
>>>return the number of drives in AL.
>>>
>>If you had tried it, you would have found out it *doesn't* work :-) :-)

I think we have it licked now!  I wrote the following program and tested
it on a PC with 1 drive and  a PC with 2 drives and it returned
the correct number of floppies:


#include <stdio.h>
#include <dos.h>

main ()
{

	int intnum;
	REGS *regsin, *regsout;

	intnum = 0x11;

	int86 (intnum, regsin, regsout);

	printf ("%d\n",(regsout->ax & 192) +1);
}


What it does is call INT 11h and check bits 6 and 7 in the ax
register.  (0 means 1 drive, etc).

(BTW REGS is a struct of ints)

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