Dismiss
InnovationQ will be updated on Sunday, Oct. 22, from 10am ET - noon. You may experience brief service interruptions during that time.
Browse Prior Art Database

Spiral Direct Access Storage Device Format for Non-Stop Multimedia Data Transfers

IP.com Disclosure Number: IPCOM000113271D
Original Publication Date: 1994-Aug-01
Included in the Prior Art Database: 2005-Mar-27
Document File: 2 page(s) / 70K

Publishing Venue

IBM

Related People

Brown, DH: AUTHOR [+2]

Abstract

Disclosed is a method of providing interruption free data transfers from Direct Access Storage Devices (DASD) for applications that need that performance, such as multimedia applications. Alternative methods are already in production on DASD with many surfaces, but this method is superior because it can be employed on DASD without a large number of surfaces and can provide continuous head motion which is inherently less disruptive.

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

Spiral Direct Access Storage Device Format for Non-Stop Multimedia
Data Transfers

      Disclosed is a method of providing interruption free data
transfers from Direct Access Storage Devices (DASD) for applications
that need that performance, such as multimedia applications.
Alternative methods are already in production on DASD with many
surfaces, but this method is superior because it can be employed on
DASD without a large number of surfaces and can provide continuous
head motion which is inherently less disruptive.

      Conventional DASD today is manufactured with data tracks on
concentric circles.  To access data on different tracks, the actuator
containing the recording heads is moved from one track to another.
There is a period of time while the heads are being moved that the
read or write function of data access cannot be used.  This occurs
when a cylinder of data is read and the head must move to the next
cylinder.  This interruption in reading and writing is undesirable in
applications where a steady data stream is required.  The invention
to be described allows DASD to be manufactured in the normal manner
with concentric servo patterns written to define the track locations.
However, the actual data in each successive sector location on a
track is written at a constant radial offset from the data in the
previous sector.  The result is that after the head reads or writes a
complete revolution with the incremental offsets in position added to
each data sector, the head is already shifted one track position at
the beginning of the next revolution.  It may begin reading the next
track without waiting to reposition the head.

      This method differs from that employed by products currently on
the market.  Those methods have data being arranged in concentric
tracks but the tracks in a cylinder are slightly offset.  Thus the
head reads a track on one surface.  At...