Subject: Re: unbootable new disk?
To: Robert Nestor <>
From: David Laight <>
List: current-users
Date: 11/27/2004 09:21:03
> Based on the wording of the "137Gig Limit" that came with this disk, 
> what I was able to find on the subject online from various disk 
> manufacturers and what I saw with two different disks on this system, I 
> suspect the 137Gig limitation is partially a BIOS problem and partially 
> an OS problem.

The root cause is that no one ever believed disks would get that big!
The ATA/IDE specification only has 28 bits available to pass the sector
number to the drive - which limits you to 137GB.

To read beyond that point you need to use LBA48 transfers (which basically
involve the sector registers being treated as a 2 deep fifo and you writing
two byte values to each register - then execting a different command byte).

This is only the latest (and probably not the last!) size limit on IDE disks!
A web search will give you most of them....


David Laight: