BIOS selects boot drive as first in the specified sequence (in BIOS setup)
that has a device that indicates it has a bootable partition
from that device it will load the boot program (mbr), which will (in current
Windows Linux etc. - post DOS systems)  load the OS selection facility from
the 'Active' partition.
Once that facility has determined which OS to load, it loads that from the
specified device (as per the attachment path, or - for USB and other
detachable devices - the selection id) and the indicated directory
Beware - Windows can run the pagefile from one, or several partitions, and
can have the registry and user profile (desktop etc) on another, so your
logged-on environment can be spread over 4, or more partitions

note the difference between partitions and drives
a drive can have several partitions - and even bootable CD's are setup that
way

The Windows OS booted from a hard drive usually assumes that you will only
access 1 partition from a CD or DVD in a drive,  so the Manage facility
usually shows 1 letter for those drives.

The OS will probably stop you changing the letter associated with the
partitions used as part of the current logged in user control set -
Active partition, OS partition, pagefile, and user profile.

Be careful about changing partition letters for drives that contain
software, or used as the source for installed software, sometimes that
software will refer to the installed from location by device type, and
sometimes it is poorly coded so it looks at the letter that was assigned
when the software was installed ( see MS Office )

So - firstly C and E are partitions on those drives
and the OS startup options probably reference those partitions by directory,
connection path, and partition sequence number within the drive
so - moving a drive from primary P-IDE cable master position to Secondary
P-IDE connection master will need the boot option location changing from
0,0,0,0 to 0,0,1,0, and as a slave  to 0,0,1,1

Don't worry too much about that if you are changing drive connections
around, just make sure the boot.ini has appropriate entries Copy and modify
as needed), and that the startup partition is still marked as Active


Now - the letters .. Windows has a file where it records the letters
associated with the partitions and drives, using the drive id codes and
partition locations, so switching the connections around will not worry the
OS, it simply finds the drives by their ID's and allocates letters as before
deleting, or adding a partition will cause problems as the OS will be
allocating letters by location, a new partition created before an old one
(by splitting an existing partition can get the letters re-allocated, and
confuse the OS

Adding at the end, or adding new drives is not such a problem as the OS will
allocate letters as it was previously set to do, then allocate spare letters
to the new partitions.

Fun aint it, but not quite as bad as before remembering the DOS/Win95
allocation was Primary partitions got allocated letters first, then the
drives were re-scanned for non-primary partitions, with the scan stopping as
soon as a partition was found that was formatted as any other type than
FAT - move a drive and all the letters could change!

JimB

----- Original Message ----- 
From: "chris adams" <[EMAIL PROTECTED]>
To: <[email protected]>
Sent: Monday, August 07, 2006 10:33 PM
Subject: drive letter assignment


> greetings - i have a machine(win xp pro) that i'm trying to change the
> letter assignments on, having no success. currently, 'c' is the serial
> ata drive, 'd' is a cd-rom, 'e' is a zip drive, and 'f' is another
> cd-rom. everything is jumpered to cable select, with both cd-roms on the
> 1st ide channel, and the zip in the master position of the second ide
> channel. i moved the zip to the  slave position on the 1st ide channel,
> and put the second cd-rom in the second ide cable, master position.
> rebooted, and the zip drive was still 'e'.  i went into control panel
> and tried to locate a means to change letters, but could not find one.
> possibly that was win 2000. it occurs to me that i may need the zip
> software to change the lettewr assignments.  help, please?
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