Browse Prior Art Database

Write Check Gaps

IP.com Disclosure Number: IPCOM000074087D
Original Publication Date: 1971-Mar-01
Included in the Prior Art Database: 2005-Feb-23
Document File: 2 page(s) / 38K

Publishing Venue

IBM

Related People

Luhre, OR: AUTHOR

Abstract

Unusable media areas caused by media defects are reduced in size by interleaving identified defect areas among recorded data blocks.

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 69% of the total text.

Page 1 of 2

Write Check Gaps

Unusable media areas caused by media defects are reduced in size by interleaving identified defect areas among recorded data blocks.

During a write operation, tape movements are monitored. This is accomplished either by tallying oscillator pulses, counting the number of bytes recorded, or counting tachometer pulses. This description assumes that tachometer pulses are counted to monitor tape displacement. Data is recorded in blocks. Shown are data blocks N-1, N, and N+1. Three defect areas are shown as residing in data block N.

When the readback circuits, not shown, detect the write errors caused by media defects, the count of tachometer pulses from a reference point 10 in the IBG (interblock gap) is registered. Even though a write error is detected, a complete data block may be recorded with all of the defects in a given area detected. In the alternative, each defect may be handled separately.

A programmed error-recovery procedure backspaces the tape to reference line 10 in the IBG. The record is then rewritten until line 12 (a predetermined distance upstream from the first defect) is reached, at which time either a postamble burst in PE mode is recorded or other identifying defect area-control codes may be recorded. Depending upon the count in the write error registers, an interleaved IBG is formed and continued until the defect areas have been passed. The interleaved gap could be much smaller than a standard IBG. Then, a second part of the data...