Browse Prior Art Database

System Code Independent Tape Device Density Support

IP.com Disclosure Number: IPCOM000109488D
Original Publication Date: 1992-Sep-01
Included in the Prior Art Database: 2005-Mar-24
Document File: 2 page(s) / 81K

Publishing Venue

IBM

Related People

Chartrand, DM: AUTHOR

Abstract

A method is described for an I/O driver to report tape density supporting text to the system for use. Using this method, new tape devices can be attached to a system with no impacts to the operating system. Other device-specific text information can be supported in the same way.

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

System Code Independent Tape Device Density Support

       A method is described for an I/O driver to report tape
density supporting text to the system for use.  Using this method,
new tape devices can be attached to a system with no impacts to the
operating system.  Other device-specific text information can be
supported in the same way.

      The input/output processor currently supports retrieving and
setting densities on the device via the read tape parameters and set
tape parameters commands.  The density support is bit-mapped into a
2-byte field for both the read and set tape parameters.  Each density
is assigned a bit which can be on or off.  On the read tape
parameters command, one and only one bit can be set by the
input/output processor to indicate the current density off the tape.
On the set tape parameters command, OS/400* may set one and only one
bit to select the density to be written to tape.

      The input/output processor can return a map to OS/400 via vital
product data (VPD).  In the VPD, we can include a table in the
self-defining characteristics which can be used when translating
between the customer displayed or requested density and the
appropriate bit for the input/output processor.  A typical
characteristic map that would be sent by the input/output processor
is shown in the figure.

      In the table, x indicates a hexadecimal value, e indicates an
EBCDIC value, and Y is an arbitrary value selected to indicate this
type of table information (other types of information or ta...