Browse Prior Art Database

Serial Data Recording

IP.com Disclosure Number: IPCOM000084392D
Original Publication Date: 1975-Nov-01
Included in the Prior Art Database: 2005-Mar-02
Document File: 2 page(s) / 31K

Publishing Venue

IBM

Related People

Lewis, DM: AUTHOR

Abstract

A plurality of data formats can be advantageously employed with serial data recorders not using an erase before write.

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 59% of the total text.

Page 1 of 2

Serial Data Recording

A plurality of data formats can be advantageously employed with serial data recorders not using an erase before write.

A normal data format is shown in A, wherein each record area has an initial clock synchronizing set of signals termed a "preamble". Following each preamble is a begin mark, which is a special character denoting the end of the preamble and the onset of data recording. The data signals have interleaved resynchronization marks; for example, every 256 data bytes. Resynchronization marks restore the phase of the clock if it is out-of-phase and identify the precise location of the data signals, for enabling recovery from error conditions existing in the preceding data signal. The resynchronization marks are repeated a plurality of times in each record.

For data security purposes, it is often desired that the record area be erased for ensuring that the previous data recording is not read by anyone. In B, an erased record area also includes a preamble, followed by a begin mark. In the first data portion, the number of the record, i.e., a number identifying the physical location of the record on the record medium, is recorded followed by repeated resynchronization marks for the extent of the record area. The repeated resynchronization marks indicate erasure.

Resynchronization marks are constructed such that any previously recorded data is completely obliterated. Additionally, when recording data that completes only a portion of the r...