Browse Prior Art Database

Peripheral Data Compression Technique

IP.com Disclosure Number: IPCOM000108969D
Original Publication Date: 1992-Jul-01
Included in the Prior Art Database: 2005-Mar-23
Document File: 3 page(s) / 91K

Publishing Venue

IBM

Related People

Jasperson, BR: AUTHOR [+3]

Abstract

Disclosed is a software technique for dynamically filtering and compressing a PC's peripheral input device data stream. This technique results in an 88% data reduction, reduced processor overhead and storage and reduced data packet dropping.

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This is the abbreviated version, containing approximately 52% of the total text.

Peripheral Data Compression Technique

       Disclosed is a software technique for dynamically
filtering and compressing a PC's peripheral input device data stream.
This technique results in an 88% data reduction, reduced processor
overhead and storage and reduced data packet dropping.

      Within an automated network emulation tool environment, the
traditional approach to data capture is to passively monitor the user
input/output peripherals and simply record every byte that passes
across in a time-tagged fashion.  Recently, this test tool's
development group, in adding pointing device (mouse) emulation
capability to its automated test tool, came up with an approach to
pack the pointing devices data stream while maintaining perceived
screen cursor resolution and reducing the number of "lost packets"
which inevitably occurs in a priority-based interrupt-driven PC
operating system.  This data filter approach is based upon a
user-selectable range of allowable pointing device data stream
reporting periods.  Fig. 1 is a diagram of the test tool environment
in which this approach was developed.

      Both the IBM and industry standard asynchronous attach mice
report in streams of three-byte packets at upwards of 40
packets/second.  These packets consist of a header/button-state byte
and a magnitude byte for each of the X and Y directions reflecting
relative incremental changes in position.

      This compression approach is as follows:  within consecutive
timing windows, all point...