Path: utzoo!attcan!uunet!microsoft!steveha
From: steveha@microsoft.UUCP (Steve Hastings)
Newsgroups: comp.os.msdos.programmer
Subject: Re: MS/PC DOS 3.3 vs 4.? (which is better?)
Message-ID: <58308@microsoft.UUCP>
Date: 17 Oct 90 18:20:39 GMT
References: <1990Oct15.025303.6582@odetics.com> <58280@microsoft.UUCP>
Reply-To: steveha@microsoft.UUCP (Steve Hastings)
Distribution: na
Organization: Microsoft International Products Group
Lines: 17

In article <58280@microsoft.UUCP> steveha@microsoft.UUCP (Steve Hastings) writes:
>DOS 4.x uses a 16-bit FAT, so it can support very large disks indeed.

Oops!  Back to school with me.  DOS 3.x had a 16-bit FAT, and still could
only have 32MB partitions.

The DOS internal "block number" was limited to 16 bits in DOS 3.x and was
the source of the 32MB limit (64k of sectors times 0.5k per sector = 32MB).
In DOS 4.x, that number is increased to 32 bits, allowing DOS to count up to
four billion sectors (an impractically large number).

Sorry about that, folks.  I bet the DOS developers are laughing at me now.
Anyway, if you are interested in the gory details of DOS, read the "Disk
Companion" chapter in the Norton Utilities 5.0 "Disk Explorer" manual.
-- 
Steve "I don't speak for Microsoft" Hastings    ===^=== :::::
uunet!microsoft!steveha  steveha@microsoft.uucp    ` \\==|