Browse Prior Art Database

Media Removal Architecture for Personal Computers

IP.com Disclosure Number: IPCOM000105959D
Original Publication Date: 1993-Sep-01
Included in the Prior Art Database: 2005-Mar-20
Document File: 4 page(s) / 143K

Publishing Venue

IBM

Related People

Osborn, NA: AUTHOR

Abstract

Described is an architectural implementation to provide a means whereby personal computers (PCs) can function with removable high performance storage devices, such as removable high performance solid state or disk subsystems. The implementation involves addressing considerations to enable a removable media to be supported on advanced technology bus attachments (ATAs) as used in PCs.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 41% of the total text.

Media Removal Architecture for Personal Computers

      Described is an architectural implementation to provide a means
whereby personal computers (PCs) can function with removable high
performance storage devices, such as removable high performance solid
state or disk subsystems.  The implementation involves addressing
considerations to enable a removable media to be supported on
advanced technology bus attachments (ATAs) as used in PCs.

      In prior art, a PC utilized rotating storage devices that were
not intended to be removable, such as the direct access storage
device (DASD).  Typically, communication between the host and the
DASD was through an AT interface, such as an AT integrated device
electronics (AT-IDE), an AT- Attachment and an internal designation
of direct bus attachment (DBA).  However, there existed no protocol
to ensure the data integrity of a removable media attached to the
system.  The concept described herein provides a means of enabling
functional communication of a removable media within an existing
structure of the AT file interface.

      With the advent of such devices as solid state file subsystems
as well as smaller high performance DASD devices, a need exists to
ensure the physical integrity of data distribution and interchange
for proper PC operation.  The common access method (CAM) committee
has defined the ATA as a means of creating a standard commodity that
can be supplied by multiple sources and used by multiple original
equipment manufacturers (OEM).  With the CAM ATA standardized,
typical PCs have employed a separate controller card and head disk
assembly (HDA).  As the drives have become smaller the controller
electronics have been integrated into the drive package, requiring a
need for a new CAM ATA.  Unfortunately, if the storage drive units
are removable, the controller electronics cannot be removed while the
system is operating without a loss of data.  With devices, such as
high capacity flex files, Bernoulli devices, removable rigid disks
and solid state memory cards, it is desirable to provide an ATA
interface for such devices.

      Since the existing ATA does not provide a means of telling the
host system that the data storage media has been removed or changed,
a DASD with a removable media must have a means of informing the
system that the storage medium has been removed or replaced.  If this
function is not provided, the integrity of the user's data cannot be
assured.  The following three examples illustrate the problems
confronting the removable media in existing conditions:

1.  The media has been removed - The only message that the ATA can
    send to the system is a "drive not ready".  This is an accurate
    report, but somewhat misleading, as "drive not ready" is most
    commonly meant to mean that the drive is broken.

2.  Media has been removed and replaced - The worst case is that a
    different piece of media has replace what was previou...