Gerry Hickman wrote:
In an eariler post I said I'd seen drive sizes reported as 8Gb with SCSI
when the drives are actually much bigger. I thought it was related to
not using a SCSI driver and BIOS (INT13) reporting wrong size, and Eric
said it wasn't. I think Eric is right, but my BIOS has been updated
since I last seen this problem, so it's impossible to say what caused it.
After further reading, it seems this kind of thing was originally more
of a problem with IDE/ATAPI drives, as opposed to SCSI. Here's an
extract from a page talking about INT13:
http://www.fixup.net/tips/20gb/20gb.htm
--- start here ---
Technical Explanation
In PC, hard drive is accessed via BIOS Interrupt 13 calls. Old Int13
routines has limit for 500MB, 8GB or 30GB drives. An extension to Int13
has been added to newer BIOS to eliminate the limit. Therefore, newer
BIOS has no this limit. For old BIOS, an overlay program, such as
MaxBlast II, can be used to load this extension before OS loading, so
the Int13 calls are translated into extension calls.
Old OSs, including DOS, Win3.xx and NT, were not aware of this extension
and therefore always need an overlay program to use large hard drives .
Newer OSs, including Linux and Win95/98/Me/2000/XP, are aware of the
extension and do not rely on an overlay to access hard drive after OS
loading. Therefore, performance and reliability of an overlay program
is not an issue once these OSs are started. However, they do matter
during OS loading and unloading and that's why some overlay programs
(such as IBM DM) cause trouble during standby and hibernation.
--- end here ---
--
Gerry Hickman (London UK)
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