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Path: utzoo!mnetor!seismo!mcvax!botter!ark!maartenj
From: maartenj@cs.vu.nl (Maarten Jan Huisjes)
Newsgroups: comp.sys.ibm.pc
Subject: Re: INT 33, fn 14
Message-ID: <997@ark.cs.vu.nl>
Date: Sun, 3-May-87 21:59:39 EDT
Article-I.D.: ark.997
Posted: Sun May  3 21:59:39 1987
Date-Received: Mon, 4-May-87 02:44:33 EDT
References: <4810@jhunix.UUCP>
Reply-To: maartenj@cs.vu.nl (Huisjes Maarten Jan)
Organization: VU Informatica, Amsterdam
Lines: 32
Keywords: Dos Interrupts Select Current Drive

In article <4810@jhunix.UUCP> ins_agwa@jhunix.UUCP (Gunther Wil Anderson) writes:
>Help.
>Interrupt 33, service 14 (Select current drive) is not returning a valid
>count of drives. I have 3, it keeps saying I have five.
>I'm using PCDOS 3.0. Does anyone out there know what's going on, or at
>least another way to get a count of drives?

The technical reference manual (3.10) says:
	"For Dos 3.00, the minimum value returned in AL is 5."
Also if you have 1 diskette drive it will still be counted as two.

To determine the real number of (diskette) drives you have to use interrupt 11H.
Syntax:	int 11H
  On return in AX:
	bit(s)
	14-15		number of printers
	  13		reserved (PCjr: serial printer installed)
	  12		game adapter attached
	 9-11		number of RS232 cards
	   8		reserved
	 6- 7		number of diskette drives installed (if bit 0 = 1)
			00 = 1, 01 = 2, 10 = 3, 11 = 4
	 4- 5		initial video mode
			01 = 40x25 color, 10 = 80x25 color, 11 = 80x25 B/W
	 2- 3		system board ram size
			00 = 16K, 01 = 32K, 10 = 48K, 11 = 64K
	   1		8087 installed
	   0		diskette installed
-- 

			Maarten Jan  Huisjes.  (maartenj@cs.vu.nl)
			{seismo|decvax|philabs}!mcvax!vu44!maartenj