Integrated Control of Distributed Volume Visualization
`Through the World-Wide-Web
`
`Cheong
`David
`
`Michael
`
`Assg MS
`Martin M.S
`Doyle Ph.D
`
`University of California San Francisco
`
`Library and Center
`for Knowledge Management
`San Francisco California 94143-0840
`
`tous access to
`
`The World-Wide-Web WWW has createda new paradgyn Jbr
`online information retrieval by providing immediate and ubiqui
`ofany typefrom data repositories
`the world The web
`
`enables not
`located throughout
`development
`access for the generic user but also more efficient and
`only effective
`We
`timey infrrmation exchange amongscienti as andresearchers
`have extended the capabilities oft/se web to include access to three-
`
`dimensional volume data sets with integrated control ofa distrib
`
`uttd client-server volume visualization
`
`This paper pro
`system
`the World-Wide- Web an overview of
`vides brief backgroundon
`new data types and
`the extensions necessay to support
`in WIVW
`description ofan implementation of this approach
`compliant distributed visualization system
`
`these
`
`Introduction
`
`visualization
`
`Viewnix
`
`Advanced scanning devices such as magnetic resonance
`tomography CT have been
`imaging MRI and computer
`and
`widely used in the fields of medicine quality assurance
`Zandt Hibbard The need to visu
`meteorology
`alize resulting data has given rise to wide variety of volume
`visualization techniques and computer graphics research groups
`number of systems to provide volume
`have implemented
`e.g AVS ApE Sunvision
`Voxel and 3D
`Mercurio VandeWettering
`Previously
`these systems have depended upon specialized graphics hard
`ware for rendering and significant
`for
`the data The
`
`expense
`ability of researchers
`
`local secondary storage
`of these requirements
`has limited the
`findings To overcome the
`to exchange
`barrier ofcost and to provide additional means ior researchers
`and examine three-dimensional
`volume data we
`to exchange
`distributed volume visualization tool
`have implemented
`purpose hardware we have
`further integrated that
`general
`visualization service with the distributed hypermedia
`Broering Kiong Robison Story system provided
`World-Wide-Web
`
`for
`
`by the
`
`Our distributed volume visualization tool
`
`\TJS utilizes
`
`1070-2385/94
`
`$04.00
`
`1994 IEEE
`
`13
`
`pool of general purpose workstations to generate three dimen
`sional representations of volume data The VIS tool provides
`integrated load-balancing across any number ofheterogeneous
`UNIX workstations e.g SGI Sun DEC etc..
`taking advantage of the unused cycles that are generally avail
`able in academic and research environments
`In addition VIS
`supports specialized graphics hardware e.g the RealityEngine
`from Silicon Graphics when available for real-time visualiza
`
`tion
`
`Distributing infurmation that
`
`includes volume data re
`document deliv
`quires the integration of visualization with
`ery mechanism We have integrated VIS and volume data into
`the WWW taking advantage of the client-server architecture
`ofWJY and its ability to access hypertext documents stored
`Nickersen We have
`anywhere on the Internet
`the capabilities of the most popular WWW client
`enhanced
`
`Mosaic
`from the National Center
`Supercomputer Applications NCSA to support volume data
`for communication
`and have defined an inrer-dient protocol
`
`for
`
`between VIS and Mosaic forvolumevisualization It should be
`
`applications
`
`noted that other
`types of interactive
`embedded within HTML documents as well Our approach
`can be generalized to allow the implementation of object
`linking and embedding over
`the Internet similar to the fea
`tures the OLE 2.0 provides users ofMicrosoft Windows on an
`individual machine
`
`could be
`
`1.1 The World-Wide-Web
`
`protocol
`
`The World-Wide-Web is
`combination
`for hyper-text documents HTTP and
`hyper-text
`mark-up language HTML
`The basic function
`ality of HTTP allows
`wide
`client application to request
`variety of data objects from server Objects are identified by
`locator URL
`universal
`resource
`that contains
`to both locate and query
`information sufficient
`HTML documents are defined by document
`
`of
`
`transfer
`
`remote server
`
`type definition
`
`Petitioner IBM – Ex. 1074, p. 1
`
`

`
`fill-in
`
`image display
`with page formatting type-face specification
`In addition Mosaic
`forms and graphical widgets
`to FTP Gopher WAIS and other
`access
`provides inherent
`network services
`
`1.3 VIS
`
`VIS is
`
`VIS
`
`simple but complete volume visualizer
`transformation e.g ro
`provides arbitrary three-dimensional
`tation and scaling specification of six axial clipping planes
`nb cuboid one arbitrary clipping plane
`and control of
`opacity and intensity VIS interactively transforms the cuboid
`and texture-maps the volume data onto the transformed geom
`Drebin
`etry It supports distributedvolume rendering
`Kaufman with run-time selection ofcomputation servers and
`Levoy with
`isosurface generation marching cubes
`software Gouraud shading for surface-based model extraction
`reads NCSA Hierarchical Data Format
`and rendering
`HDF volume data files and has
`interface utility
`graphical
`to import volume data stored in other formats
`
`It
`
`VI5UALIz.kTIoN
`
`SERvERS
`
`DATA CEmR
`
`VIS Distributed Volume Visualization Tool
`
`VIS is
`
`tool
`
`highly modular distributed visualization
`following the principles of client/server architecture figure
`and consisting of three cooperating processes VIS Panel and
`VRServers The 115 module handles the tasks oftransforma
`don texture-mapping isosurface extraction Gouraud shad
`ing and manages load distribution in volume rendering VIS
`to its own top-level
`produces images that are drawn either
`window when running stand-alone
`shared window
`or to
`buffer when running as
`cooperative process The
`system
`Panel module provides
`graphical user-interface for all VIS
`functionality and communicates
`The
`to \TIS
`VRServer processes execute on
`heterogenous pool of general
`purpose workstations and perform volume rendering at
`request of the VIS
`The three modules are integrated
`process
`as shown in figure when cooperating with another process
`simple output window is displayed when no cooperating
`
`state changes
`
`the
`
`process is specified
`
`2.1 Distributed Volume Rendering
`
`Volume rendering algorithms require asignificant amount
`resources However
`of computational
`these algorithms
`excellent candidates for parallelization VIS distributes
`the
`volume rendering among workstations with greedy algo
`the work to faster
`rithm that allocates
`larger portions of
`VIS segments the task ofvolume render
`ing based on scan-lines with
`sized to balance compu
`segments
`tational effort versus network transmission time Each of the
`
`machines
`
`are
`
`HIGH SPEED LocAl NErwoRk
`
`Gsps
`
`Figure
`
`VIS clientIserver model
`
`DTD of
`the Standard Generalized Mark-up Language
`SGML These documents are returned to WWW clients and
`
`presentation
`
`following hyper-links
`
`that
`
`lead to
`
`are presented to the user Users are able to interact with the
`document
`other HTML documents or data objects The client applica
`tion may also directly support other
`Internet services such as
`FTP Gopher and WAIS
`or may utilize gate
`requests and return HTML
`ways that convert HTTP protocol
`documents
`however
`the user is presented
`with common resulting data format HTML and all
`accessible via URLs
`
`In all
`
`interactions
`
`links are
`
`1.2 Mosaic
`
`The National Center
`for Supercomputer Applications
`NCSA has developed one ofthe most functional and popular
`World-Wide-Web clients Mosaic This client is available via
`public FTP for the most popular computer
`interfaces Motif
`Windows and Macintosh Mosaic interprets majority ofthe
`HTML DTD elements and presents the encoded
`information
`
`14
`
`Petitioner IBM – Ex. 1074, p. 2
`
`

`
`user-selected
`
`computation servers fetches
`
`segment for render
`ing via remote procedure calls RPC returns results and fetch
`The servers effectively compete for seg
`another segment
`ments with faster servers processing more segments per unit
`time ensuring relatively equal load balancing across the pool
`931 shows
`Function of both the
`
`that
`
`Analysis of this distribution algorithm
`the performance improvement
`number ofsegments and the number ofcomputational
`servers
`with the optimal number of sections increasing directly with
`the number of available servers Test results indictate that
`
`is
`
`flattens out between
`
`performance
`improvement
`distributed across an available pool of four servers
`segments
`Although this algorithm may not be perfect
`it achieves accept
`able results
`
`10 to 20
`
`2.2 Cooperative Visualizaton
`
`The \IS client together with its volume rendering serv
`ers may be lauched by another application
`collectively
`visualization server The two requirements of cooperation are
`shared window
`for the rendered image and
`buffer
`system
`limited number of inter-process messages
`1/IS
`support
`and the initiating application communicate via the ToolTalk
`
`for
`
`as
`
`to visualize
`service passing messages specifying the data object
`for visualization and maintaining state
`as well
`as options
`regarding image display The VIS Panel application appears as
`new top-level window and allows the user control of the
`visualization tool
`
`Visualization with Mosaic
`
`both
`
`VIS as
`
`the Mosaic WWW browser to support
`We have enhanced
`three-dimensional data object and communication with
`HTTP servers
`coopezraring application
`figure
`from clients e.g Mosaic by transferring
`respond to requests
`hypertext documents to the client
`Those documents may
`contain text and images as intrinsic elements and may also
`links to any arbitrary data object e.g audio
`contain external
`Mosaic may also communicate with other
`video etc...
`Internet servers e.g FTP either directly
`translating request
`results into HTML on demand
`or via
`gateway that provides
`translation services As aWWW client Mosaic communicates
`with the servers of interest
`in response to user actions e.g
`connection and requesting
`selecting hyperlink initiating
`the document specified by the URL The server delivers the file
`specified in the URL which may be HTML document or
`variety of multimedia data files
`for example images audio
`files and MPEG movies
`and Mosaic uses the predefined
`SGML DTD for HTML to parse and present the information
`Data types not directly supported by Mosaic are displayed via
`user-specifiable external applications and we have extended
`
`that paradigm to both include three-dimensional
`as well as to integrate the external applications more completely
`with Mosaic
`
`volume data
`
`3.1 Mosaic 3D image support
`
`that
`
`is
`
`is defined
`
`We have extended the HTML DTD to support
`three-
`new SGML ele
`dimensional data via the introduction of
`ment EMBED This element provides information to the
`presentation system i.e Mosaic about
`the content
`referenced in the document The EMBED element
`in the HTML DTD as shown in Example
`which is translated
`as SGML document
`tag EMBED contain
`instance element
`four required attributes TYPE the type of the
`ing no content
`external application in the MIME-type format HREF the
`of the datafile WIDTH the window width
`location/URL
`and HEIGHT the window height The TYPE attribute give
`to accomodate different
`this specification the flexibility
`types
`In HTML document
`3D image
`of external applications
`which
`element would be represented as shown in Example
`drawing-area window of width
`may be interpreted as create
`400 pixels height 400 pixels and use the application associated
`to hdffvolume MIME content-type
`data
`to visualize the
`the HTTP
`located
`Embryo.hdf
`at
`www.library.ucsfedu
`
`server
`
`sire
`
`3.2 Interface with Mosaic
`
`The VIS/Mosaic
`software system consists of three ele
`ments VIS Mosaic and Panel Currently the VIS applica
`tion communicates with Mosaic via ToolTalk
`but
`the
`system will work with any inrerclient communication proto
`col When Mosaic interprets the HTML tag EMBED it
`in the document page presenta
`drawing area widget
`creates
`tion and requests ashared buffer or pixmap from thewindowing
`In addition Mosaic
`results
`system to receive visualization
`launches the Panel process specifying the location of the data
`to render and identifying the shared image buffer The
`object
`Panel process begins execution by first
`verifying its operating
`parameters then launching the VIS process The Panel process
`elements for data
`also presents rhe user with the control
`the communication
`manipulation and manages
`whole VIS application and Mosaic
`The VIS process on the other hand serves as
`rendering
`engine It executes the visualization commands From the Panel
`segments from various
`integrates the image data
`process
`and presents
`VRServers
`the complete array of image data to
`
`between
`
`the
`
`the Panel
`
`Thus the scenario
`
`will be
`
`Panel
`
`following users action on the Panel
`commands to the VIS
`
`issues visualization
`
`rendering engine
`
`VIS sends
`
`rendering requests
`
`to
`
`15
`
`Petitioner IBM – Ex. 1074, p. 3
`
`

`
`Figure
`
`VIS embeded within Mosaic for interactive visualization in HTML document
`
`VRServers then gathers the resulting image segments
`the returned image data then writes it
`Panel
`fetches
`to the
`Panel notifies Mosaic upon completion and
`pixmap
`Mosaic bit-blots the pixmap contents into its corresponding
`DrawingArea widget The interprocess communication
`in more details under section 3.3 The
`will be addressed
`
`issue
`
`configuration of this software system is depicted in figure
`
`3.3 Interclient communication
`
`We recognized the minimum set of communication pro
`tocols between Mosaic and
`particular Panel process
`Messages from Mosaic to
`Panel process include the
`
`following
`
`ExitNotify
`itself.when Mosaic exits
`
`requesting the Panel
`
`to terminate
`
`ii MapNotify requesting the Panel
`the screen when the HTML
`document
`
`to map itself to
`the
`
`containing
`
`16
`
`is visible
`
`DrawingArea corresponding to the above panel
`iii UnmapNoti1r
`to unmap/
`requesting the Panel
`iconi itselfwhen the HTML page containing the DrawingArea
`is cached
`corresponding to the above Panel
`Messages from Panel process to Mosaic may be one
`of the following
`
`RefreshNotifr
`the shared pixmap and
`correspinding DrawingArea
`
`informing Mosaic of an update in
`Mosaic to update the
`
`requesting
`
`is
`
`informing Mosaic the Panel
`ii PanelStartNorify
`started successfully and ready to receive messages
`informing Mosaic the Panel
`iii PanelExitNocify
`exiting and Mosaic should not send any more messages to the
`Panel
`We have packaged
`the above protocols and all the required
`library Modification ofan existing
`messaging functions into
`external application merely involves registration of the external
`applications messaging window the window to receive Mosaics
`messages installation of callback functions corresponding to
`
`is
`
`Petitioner IBM – Ex. 1074, p. 4
`
`

`
`the
`
`messages
`
`from Mosaic and addition of message-sending
`is summarized in Table
`The protocol
`routine invocations
`
`Messages
`
`ExitNotify
`
`MapNotify
`
`UnmapNotify
`
`RefreshNotifr
`
`PanelStartNotify
`
`PanelExitNorify
`
`Descriptions
`Mosaic exiting
`DrawingArea visible
`DrawingArea cache
`DrawingArea
`Panel starting
`
`update
`
`Panel exiting
`
`Table
`
`MosaicNlS IPC communication
`
`Results
`
`in
`
`relatively
`
`workstations
`
`and
`
`The results of the above implementation are very encour
`The MosaicIVIS sucesslully allows users to visualize
`aging
`HDF volume datasets from various HTTP server Sites Fig
`snapshot of the WWW visualizer Distributing the
`shows
`volume rendering loads results in
`remarkable speedup
`Our performance
`ananlysis with
`image computations
`homogeneous pool of Sun SPARCstation 2s on
`calm network produced reasonable results Figures 4a 4b and
`4c
`Three trials
`The time-versus-number-of-
`per plot
`curve decreases as more servers participate
`plateaus when the number of SPARCstations is 11 in the case
`for l28x128
`of 256x256 image
`for 192x192 image and
`image The speed increases at the plateaus are very significant
`about 10 times for the 256x256 image times for the 92x192
`image and
`The outcomes
`the 128x128 image
`times for
`that performance improvement
`suggest
`number of volume rendering servers Furthermore the opti
`mal number of workstations and the speed increase are larger
`when the image size is bigger This is in complete agreement
`with Giertsens analysis We have also successfully tested the
`software system in an environment
`consisting of heterogenous
`SGI Indigo2 R4400/1 50MHz two SGI Indy
`workstations
`133MHz
`R4000PC/100MHz DECAIpha3000/500witha
`two Sun SparcStations 10 and two Sun
`Alpha processor
`which were located arbitrarily on an Ethernet
`SparcStations
`network To our knowledge this is the first demonstration of
`client/server visual
`the embedding of interactive control of
`ization application within multimedia document
`in distrib
`uted hypermedia environment such as the World Wide Web
`
`is
`
`function of the
`
`Ongoing/Future work
`
`We have begun working on several extensions and im
`provements on the above software system
`
`ELEMENT
`ATTLIST
`
`Example
`
`EMPTY
`
`EMBED
`EMBED
`HREF
`TYPE
`WIDTH
`HEIGHT
`
`REQTJIRED
`REQUIRED
`REQUIRED
`REQUIREiJ
`SGML definition for EMBED element
`
`%URL
`CDATA
`NUMBER
`NUMBER
`
`EMBED
`HREFhttp//host/.../Embryo.hdf
`TYPEr hdf /volume
`WIDTH400
`HEIGHT400
`
`Example
`
`EMBED element usage
`
`5.1 MPEG Data Compression
`
`The data transferred between the visualization servers and
`
`servers packaged
`
`the clients consists of the exact byte streams computed by the
`in the XDR machine independent
`format
`One way to reduce network
`transferring time would be to
`compress the data before delivery We propose to use the
`MPEG compression technique which will not only perform
`redundancy reduction but also
`quality-adjustable
`entropy
`Furthermore the MPEG algorithm performs
`reduction
`
`ISTERCLIENT
`
`Cm uooN
`
`___________
`
`Visuntzrnow
`
`COMMANDS
`
`IMAGE
`Drn
`
`vis
`
`RENDERING
`Rucsrs
`
`Iust
`SEGMENTS
`
`VR5ERVERs
`
`Communication among Mosaic VIS
`Figure
`and distributed rendering servers
`
`17
`
`Petitioner IBM – Ex. 1074, p. 5
`
`

`
`interframe beside
`
`intraframe compression
`Consequently
`between the current and the
`only the compressed difFerence
`last frames is shipped to the client
`
`database PDB displaying program and the xv 2D image
`Mosaic PDB visualization
`processing program to create
`server and Mosaic 2D image processing server
`
`5.2 Generalized External-Application-to-Mosaic-Docu
`
`5.3 Multiple Users
`
`ment-Page Display Interface
`
`distributed visual
`
`The protocols specificd in Table
`are simple and general
`enough to allow most image-producing
`programs be modified
`the Mosaic document page We have successfully
`to display
`incorporated an in-house CAD model renderingprogram into
`Mosaic Our next undertakings will be to extend the protein
`
`With multiple users the VIS/Mosaic
`ization system will need to manage
`multiple users utilizing the same computational
`servers will
`slow the servers down significantly The proposed solution is
`The server
`resource manager will allocate
`depicted in Fig
`servers per VIS client
`those
`servers are not
`request only if
`
`the server
`
`resources since
`
`.10.00
`
`Time sec
`
`Number of Servers
`
`192x192
`
`256x256
`
`14
`
`00
`
`Volume Size
`
`Figure
`
`Volume rendering performance for 1282 1922 and 2562 data sets
`
`18
`
`Petitioner Microsoft Corporation Ex 1074
`
`Petitioner IBM – Ex. 1074, p. 6
`
`

`
`workstation Furthermore these visualizations can be accessed
`
`and hypergraphics
`
`links
`
`via the WWW through hypertext
`within an HTML page
`Future implementations
`types of embedded applications will
`approach using other
`allow the creation ofa new paradigm for the online distribution
`of multimedia information via the Internet
`
`of this
`
`References
`
`Argiro
`
`Seeing in Volume Pixel July/August
`39
`
`1990 35-
`
`Avila
`
`Sobierajski
`
`Towards Com
`and Kaufman
`prehensive Volume Visualization System Vi
`sualization 92 Proceedings
`IEEE Computer
`Society Press October 1992 13-20
`
`Andteessen
`
`NCSA Mosaic Technical Summary from
`FTP site ftp.ncsa.uiuc.edu
`May 1993
`
`Bloomer
`
`Power Programming with RPC OReilly
`Associate September 1992 401-451
`
`Sundsten J.W Knowledge-based
`Brinkley J.F Eno
`information
`client-server approach to stuctural
`retrieval the Digital Anatomist Browser Com
`puter methods and Programs in Biomedicine
`Vol.40 No
`June 1993 131-145
`
`Broering
`
`Drebin
`
`Flanders
`
`Georgetown University The Virtual Medi
`cal Library Computers in Libraries Vol 13
`No
`February 1993 13
`
`Volume
`and Hanrahan
`Carpenter
`Rendering Computer Graphics Vol 22 No
`August 1988 64-75
`
`Hypertext Multimedia Software Bell Atlantic
`DocuSource Computers in Libraries Vol 13
`No 1January 1993 35-39
`
`Gelerg
`
`Volume Rendering in AVS5 AVS Network
`11-14
`news Vol
`
`Issue
`
`Giertsen
`
`and Petersen
`
`Parallel Volume Rendering on
`IEEE Computer
`Network of Workstations
`Graphics and Applications November
`1993
`16-23
`
`between the resource
`overloaded Otherwise negotiation
`manager and the VIS client will be necessary and perhaps the
`resource manager will allocate less busy alternatives to the
`client
`
`5.4 Load Distributing Algorithm
`
`Since the load distributing algorithm in the current VIS
`the most optimal
`load distribution
`implementation is not
`to see some improvement
`solution we expect
`implementation which will be using sender-initiated
`rithms described in
`
`in the future
`
`algo
`
`VIsuALIz.noN
`
`SERVER
`PocEss
`
`POOL
`
`Nflwon
`
`NmvoRo
`
`REQO
`
`SERvILL
`
`PROCESS
`
`ALLOCATION
`
`ENCODtD
`IMAGE DATA
`
`COMMANDS
`
`Nnwon
`
`BOUNDARY
`
`CLIENT
`
`VIsuAuzaTIoN
`
`PRocEssEs
`
`Figure
`
`Server Resource Management
`
`Conclusions
`
`Our system takes the technology of networked multime
`dia system especially the World Wide Web
`step further by
`proving the possibility of adding new interactive data
`types to
`both the WWW servers and clients The addition of the 3D
`in the form of an HDF file to the WWW
`volume data object
`is now
`has been welcomed by many medical
`researchers for it
`possible for them to view volume datasets without
`
`high-cost
`
`19
`
`Petitioner IBM – Ex. 1074, p. 7
`
`

`
`Jager
`
`Osterfeld
`
`and Hornung
`Ackermann
`BuildingaMultimedia ISDN PC IEEE Com
`puter Graphics and Applications September
`1993 24-33
`
`Kaufman
`
`Volume Graphics
`Cohen
`and Yagel
`Computer July 1993 51-64
`
`Obraczka
`
`Pominert
`
`and Li
`Danzig
`Discovery Services Computer Vol 26 No
`September 1993 8-22
`
`Internet
`
`Resource
`
`Riemer
`
`Schuberr
`Schiemanri
`Hochne K-H Methods and Appli
`Tiede
`cations ofMedical 3D-Imaging SIGGRAPH
`93 course notes for volume visulization 68-97
`
`and Tan T.A hypertext-like approach to navigat
`ing through the GCG sequence analysis pack
`age ComputerApplications in the Biosciences
`Vol.9 No
`1993 211-214
`
`Robison
`
`The Changing States of Current Cites The
`Evolution of an ElectronicJournal Computers
`in Libraries Vol 13 No
`June 1993 21-26
`
`from Volume Data IEEE
`Display of Surfaces
`Computer Graphics and Applications Vol
`No
`May 1988 29-37
`
`Shivaratri N.G Krueger
`Load Distrib
`and Singhal
`uting for Locally Distributed Systems Com
`puter December 1992 33-44
`
`Kiong
`
`Levoy
`
`Lorensen
`
`Hennessy
`
`and Gupta
`
`Scaling Parallel Pro
`and
`Methodology
`grams for Multiprocessors
`Examples Computer July 1993 42-49
`
`OGorman
`Fox
`and Jagadish
`Schaper
`H.V The RightPages Image-Based Electronic
`Library for Alerting and Browsing Computer
`September 1992 17-26
`
`apE 2.0 Pixel November/December
`VandeWettering
`1990 30-35
`
`Woodward
`
`Interactive Scientific Visualization of Fluid
`Flow Computer Vol 26 No 10 June 1993
`13-25
`
`Zandt W.V
`
`New lnlook On Life UNIX Review Vol
`No
`March 1989 52-57
`
`Cline H.E Marching Cubes
`High Reso
`lution 3D Surface Construction Algorithm
`Computer Graphics Vol.21 No.4 July 1987
`163-169
`
`Singh
`
`Story
`
`Mercurio
`
`Khoros Pixel March/April 1992 28-33
`
`Narayan
`
`Sensharrma
`
`Sabherwal
`
`ization of
`
`Santori E.M Lee A.A
`Toga A.W Animated visuil
`three dimen
`high resolution color
`sional digital computer model of the whole
`human head International
`Journal of Bio
`Medical Computing Vol 32 No
`1993 7-17
`
`January
`
`Nickerson
`
`from CERN
`WorldWideWeb Hypertext
`in Libraries Vol 12 No 11 De
`Computers
`cember 1992 75-77
`
`20
`
`Petitioner IBM – Ex. 1074, p. 8