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Logical Addressing Extension for Disk Drive Units

IP.com Disclosure Number: IPCOM000099224D
Original Publication Date: 1990-Jan-01
Included in the Prior Art Database: 2005-Mar-14
Document File: 2 page(s) / 63K

Publishing Venue

IBM

Related People

Bealkowski, R: AUTHOR

Abstract

A technique is described whereby a software for personal computers enables two or more storage devices (DASDs) to be logically for operational purposes. Described is the use of logical address extension to enable multiple DASD devices appear as a single DASD device.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 64% of the total text.

Logical Addressing Extension for Disk Drive Units

       A technique is described whereby a software for personal
computers enables two or more storage devices (DASDs) to be logically
for operational purposes.  Described is the use of logical address
extension to enable multiple DASD devices appear as a single DASD
device.

      Typically, a personal computer system DASD is treated as
individual unit.  This limits the effective size of a file to the
capacity of the individual drive, not the sum size of all DASD
devices that may be made available to system.  For example, a system
with two disk drives, with the familiar DOS method, would generally
be as the "C" drive and the "D" drive.  At the BIOS the drives are
referred to as drive 80 hex and drive hex, respectively.

      Occasionally, it is desirable to refer to both drives as single
unit, with a capacity equal to the sum of the of the individual
drives.  The concept described provides a logical drive extension, so
as to combine or more physical drives into one extended logical
drive. extension is called the logical drive extension (LDE). is
significant to note that the LDE implementation is not to the BIOS
level, but could be implemented to hardware controllers or as part of
the system.

      The implementation of the the LDE at the BIOS level that BIOS
treat two or more physical disk drives as larger drive.  The block
diagram illustrates how mapping used in the LDE.  A single logical
drive is...