Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!samsung!bragi!dj
From: dj@bragi.ctron.com (DJ Delorie)
Newsgroups: comp.os.msdos.programmer
Subject: Re: Maximum hard disk capacity
Message-ID: <1405@bragi.ctron.com>
Date: 6 Apr 91 19:13:19 GMT
References: <1991Apr4.230824.23481@novell.com>
Organization: None whatsoever
Lines: 17

In article <1991Apr4.230824.23481@novell.com> rap@la.excelan.com (Robert A. Pease) writes:
>Cylinders = 0 - 1023
>Heads     = 0 - 15
>Sectors   = 0 - 31
>
>If I do my math right, this means that there are a total of 16384
>sectors that the BIOS can address (1024 * 16 * 32 = 16384).  At 512 Kb
>per sector, the maximum size HDU that the BIOS can get to is 262 Mb.

The IBM BIOS Technical Reference Manual does not put such a limit on
the number of sectors, although the hard drive card may, allowing 8
bits (0-255).  Same for heads, which get 6 bits (0-63).  Combined, you
get 24 bits of sector addressing, for a total of 8 Gb per HDU.  Most
ESDI and SCSI cards work this way.

DJ
dj@ctron.com