Date: Tue, 13 Feb 1996 16:49:51 +0200 (IST)
From: Eli Zaretskii <eliz AT is DOT elta DOT co DOT il>
To: kaikow AT standards DOT com
Cc: djgpp AT delorie DOT com
Subject: Re: bios


On Mon, 12 Feb 1996 kaikow AT standards DOT com wrote:

> Where are the valid values for the device numbers documented?
> I thought that the device numbers were just 0, 1, 2, ...
> 
> The following program works for devices A and B, but not for C.

This is BIOS, not DOS.  DOS indeed enumerates drives starting from 0 in 
the order it sees them when your system boots, so 0 = A:, 1 = B:, 2 = C: 
etc.  But BIOS treats floppies and hard disks differently (not 
surprisingly, because they usually use entirely different methods of 
moving the data), so 0 and 1 are still A: and B:, but the hard disks 
start with 0x80 (if the 7th bit is set, BIOS knows it's a hard disk).  So 
C: is 0x80, D: is 0x81 (assuming D: is the second hard disk), etc.