Browse Prior Art Database

Interblock Gap Measurements

IP.com Disclosure Number: IPCOM000073629D
Original Publication Date: 1971-Jan-01
Included in the Prior Art Database: 2005-Feb-22
Document File: 2 page(s) / 28K

Publishing Venue

IBM

Related People

Keffeler, JR: AUTHOR

Abstract

In higher performance tape drives, it is desirable to provide a precise indication of IBG (interblock gap) lengths. Such measurements are useful in diagnostics related to tape drive performance as well as in tape motion control.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 87% of the total text.

Page 1 of 2

Interblock Gap Measurements

In higher performance tape drives, it is desirable to provide a precise indication of IBG (interblock gap) lengths. Such measurements are useful in diagnostics related to tape drive performance as well as in tape motion control.

During normal operation or during a diagnostic mode, an IBG is written in a first direction of travel. This is accomplished by writing two successive blocks of data separated by an area of no recording. Then a command "time the IBG" is issued by a CPU to the I/O controller associated with the tape drive. The tape is then backed such that the read head is over the upstream block of data signals. Then the controller causes the tape drive to read in a forward direction. In a microprogram controller, short microloop 10 is entered which senses for end of data in the upstream block. As soon as the last byte of data is sensed in step 11, a software timer is initiated. In an alternative embodiment, this may be an oscillator driven counter. Next, another short microroutine 12 is entered which senses for start of data of the immediately downstream block of data signals. As soon as the start of data is detected, the timer is stopped and read out in step 13. Then a normal ending sequence for stopping a tape drive is performed and the metered time is sent to the CPU in step 14 for diagnostic or operational purposes.

The CPU then converts the metered time into distance and compares same with IBG specifications. An advantage...