Browse Prior Art Database

File Record Randomizer

IP.com Disclosure Number: IPCOM000101482D
Original Publication Date: 1990-Aug-01
Included in the Prior Art Database: 2005-Mar-16
Document File: 2 page(s) / 48K

Publishing Venue

IBM

Related People

Phillips, M: AUTHOR

Abstract

Disclosed is a randomizer for relative track addresses in a disk file. It allows a record to be positioned on a unique track within the file. The benefit of using a relative track address, rather than a specific position, is that collisions can occur with specific positioning and overflow logic is required. With relative track address positioning, if any collisions occur, the record can be repositioned anywhere on the track.

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File Record Randomizer

       Disclosed is a randomizer for relative track addresses in
a disk file.  It allows a record to be positioned on a unique track
within the file.  The benefit of using a relative track address,
rather than a specific position, is that collisions can occur with
specific positioning and overflow logic is required.  With  relative
track address positioning, if any collisions occur, the record can be
repositioned anywhere on the track.

      The randomizer can be used when direct record access is
required to a file.  Input to the randomizer is the key of the
record, key length and the total number of tracks in the file.  The
key is treated as a large binary number and is padded on the right
with 2 to 5 bytes of binary zeros to make a number of full words.
This is then divided by a specially selected fixed number to produce
a remainder. (The specially selected number is 54601 which forms a
unique division when trying to calculate the relative track address.)
The remainder is then divided by the number of tracks to produce a
second remainder which is the relative group number.  The relative
track number is then used by an I/O routine to either read or write
the data.

      A tested routine flow diagram is shown in the figure.