Browse Prior Art Database

Detection of End of Track

IP.com Disclosure Number: IPCOM000103126D
Original Publication Date: 1990-Jun-01
Included in the Prior Art Database: 2005-Mar-17
Document File: 1 page(s) / 32K

Publishing Venue

IBM

Related People

Leung, PL: AUTHOR [+3]

Abstract

The control unit of a direct access storage device (DASD) processes look-ahead indices as soon as the end-of-track signal has been detected. The device interface sets up an end-of-track indicator for the channel. The channel processes the index indicator and allows other processes to execute. The control unit is thereby allowed to perform house-keeping functions during the time the channel command word encounters an end-of-track signal and goes to an index condition.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 100% of the total text.

Detection of End of Track

      The control unit of a direct access storage device (DASD)
processes  look-ahead indices as soon as the end-of-track signal has
been detected.  The device interface sets up an end-of-track
indicator for the channel. The channel processes the index indicator
and allows other processes to execute.  The control unit is thereby
allowed to perform house-keeping functions during the time the
channel command word encounters an end-of-track signal and goes to an
index condition.

      If the end-of-track signal is located a distance from the index
position, the channel interface has sufficient time to allow other
processes to execute.  The device interface sends an end-of-track
signal to the channel interface.  If the index is encountered in a
short time after the end-of-track signal, the channel will process
the next command in the usual manner.  If, however, the index is not
immediately encountered, the control unit will command the devices to
go to an index state and permit another process to execute from the
idle loop.  The channel interface then processes the next command
when the index is sensed.

      Anonymous.