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Browse Prior Art Database

Media Directory With System Useability Features

IP.com Disclosure Number: IPCOM000100113D
Original Publication Date: 1990-Mar-01
Included in the Prior Art Database: 2005-Mar-15
Document File: 4 page(s) / 129K

Publishing Venue

IBM

Related People

Batalden, GD: AUTHOR [+4]

Abstract

A media logical format and directory structure have an ability to: - dynamically add additional file attributes, - initial program load (IPL) multiple systems from one media, and have multiple code loads for a single system, - associate "other data" with a data file, - define a character set used when creating each data file, and - define a character set used for the directory.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 52% of the total text.

Media Directory With System Useability Features

       A media logical format and directory structure have an
ability to:
-  dynamically add additional file attributes,
-  initial program load (IPL) multiple systems from one media, and
have multiple code loads for a single system,
-  associate "other data" with a data file,
-  define a character set used when creating each data file, and
-  define a character set used for the directory.

      This R/W optical directory was intended for interchange.
Therefore, to accommodate multiple systems, the known commonly used
attributes are included in the directory.  These include a "hidden
file" attribute of PC DOS files and a file "expiration date" used by
AS/400.  See Fig. 1 for a diagram of the attributes in a directory
entry.

      No matter what attributes are included, somebody eventually
finds a "need" for another attribute.  Past directories are not
extendable, and some other solution is necessary.  The directory
includes what is essentially a pointer to a list of "extended
attributes".  In normal usage, this list is null.  But, if requested,
the file system associates a value with an identifier and records it
in the architected extended attribute area.  Later, a user inquires
about a value of a particular named attribute.  The file system
responds that the attribute is not specified or with a value stored
previously.  See Fig.  2 for a diagram of the attributes in a
directory entry with extended attributes.

      The extended attributes are managed as a pair of user-supplied
parameters.  A first is the attribute "name", and a second is the
"value" assigned to that name.

      Another problem to consider when dealing with
interchangeability between systems is the need to possibly IPL
multiple systems.  Currently, IPL code is traditionally placed
"first" on a media.  This makes it easy to find for simple IPL code
which is probably executing from ROS (read-only storage) which is
part of the machine hardware.

      Architecture of the logical data format includes a reservation
of the first 4 device blocks for "inflexible system" IPL code--IPL
code for systems which are unable to be more flexible.

      For systems where optical media were considered, a second IPL
area is defined.  This area is a group of pointers to IPL code files.
 This second area is in many ways a very simple directory to a
limited number of files on the media.  Within this area, each entry
consists of an "ID" field followed by a pointer to a location on the
media.  To IPL, a machine reads this second IPL area, scans for the
desired "ID", and then loads code from the indicated location.

    ...