Publications and Papers, Rich Parry, W9IF

Areas of interest include: Wireless Packet Networks, Oxygen Monitoring Systems, Programmable Electronic Safety Systems, Computerized Security Systems, telecommunications, operating systems, speech synthesis, speech recognition, management tools, and radioteletype. On the non-techical side, I have written several articles on Paragliding.

The "pdf" version of the papers available here are the versions submitted for publication and not necessarily the version that was published. Publishers may modify the submitted paper to meet space and readership requirements and may even change the title of the paper. PDF files below require Adobe Acrobat Reader which is freely distributed.

1. "Flytec 5020 GPS Flight Instrument: Product Review" Paraglider Magazine Volume 4, No. 2 (July 2005), pp. 44-47.
   This paper provides a review of the Flytec model 5020 GPS Vario flight instrument. Also included is a review of Flychart, a Windows software application used to configure, upload, and analyze flight information from the 5020. An overview of key features of the instrument is provided along with personal experiences using it. Available in pdf format.
2. "Radio Active Pilot: Part 4 Amateur Radio Based Weather Station" Paraglider Magazine Volume 4, No. 1 (April 2005), pp. 52-53.
   In this installment of the series on radios and paragliding, we describe how amateur radio can be used to monitor weather conditions at remote flying sites using a computer or cell phone. A high level overview of the technology and system architecture is provided. Web site addresses are also provided for additional information. Available in pdf format.
3. "Radio Active Pilot: Part 3 Amateur Radio and the US Nationals" Paraglider Magazine Volume 3, No. 4 (Jan 2005), pp. 50-51.
   In this installment of the series on radios and paragliding, we describe an advanced application in which amateur radio was used for position tracking of pilots during the 2004 US Hang Gliding Nationals held in Big Spring, Texas in August. Available in pdf format.
4. "Radio Active Pilot: Part 2 Getting an Amateur Radio License" Paraglider Magazine Volume 3, No. 3 (Oct. 2004), pp. 52-55.
   In Part 2 of this series we discuss the process for getting an amateur radio license, the classes of licenses, the exam, and the advantages that a license provides a pilot. Purchasing and using amateur radio equipment and how a repeater can be used to extended coverage are also presented. Available in pdf format.
5. "Radio Active Pilot: Part 1 Using Radios Legally" Paraglider Magazine Volume 3, No. 2 (July 2004), pp. 52-53, 70.
   In Part 1 of this series on radios and paragliding, we describe the rules and regulations for using USHGA radio frequencies and the process for obtaining a special skills signoff. A description of radios and how to use them is provided. A brief introduction to amateur radio is provided along with the advantage of holding such a license. Special attention is given to the legal aspects of using radios. Available in pdf format.
6. "Flying Maui" Hang Gliding and Paragliding March, 2004, pp. 53-59.
   This paper describes flying experiences in Maui, Hawaii. It addresses the unique flying conditions that are endemic to Maui and the need to have good forward launching skills. A description of the Poli Poli flight park on Maui is provided along with conditions one is likely to find there. A short history of Chuck the duck, the flying co-pilot is included along with several pictures of the flight park Available in pdf format.
7. "WAPaprs: APRS on a Cell Phone" 22nd ARRL Digital Communications Conference Proceedings, Hartford, Connecticut, September 19-23, 2003 pp.135-139.
   WAPaprs is an application to display APRS information on a cell phone that supports the Wireless Application Protocol (WAP). It was written to provide useful APRS data within the size, memory, color, and bandwidth limitations of a wireless handheld device. The paper includes a description of all menu options and example displays. Available in pdf format.
8. "Flying in the Wireless World" June, 2003
   This paper describes the rules and regulations for using USHGA radio frequencies to make flying more enjoyable and safe. It also discusses the process for obtaining the USHGA special skills signoff. Amateur radio is proposed as a supplement to USHGA frequencies. The process for obtaining an amateur radio license is discussed as well as the advantages that such a license provides. A description of an amateur radio based weather station that gives pilots weather conditions at remote sites is included. Available in pdf format.
9. "APRS Weather Station: Amateur Radio and Paragliding" QST Magazine August, pp. 28-33
   This paper describes how amateur radio is being used to measure and display weather conditions and foster safe communication while paragliding. The design and configuration of a remote stand-alone APRS weather station forms the basis for the system. The weather station is located at the Torrey Pines Gliderport overlooking the Pacific Ocean in San Diego, CA. The station is used by hundreds of pilots in Southern California to determine when weather conditions will support flight. Original version in pdf format. Editorial changes were made to the original version. Magazine version in pdf format.
10. "cdma2000 1xEV-DO: A 3G Wireless Internet Access System" IEEE Potentials Oct/Nov 2002, pp. 10-13.
    This paper provides an overview of CDMA2000 1xEV-DO, also referred to as HDR (High Data Rate) and officially recognized as IS-856, a 3G standard. 1xEV-DO is a wireless telecommunications standard optimized for high-speed cellular data communication. An overview of the specification, along with a description of key characteristics of the specification is provided. Special attention is given to describing the differences between data and voice that support the design of a specification to efficiently transfer data. Available in pdf format.
11. "The Road to 3G" Published under the title "Overlooking 3G" IEEE Potentials Oct/Nov 2002, pp. 6-9.
    This paper provides a high level overview of 2G and 3G wireless cellular technologies and the expected evolutionary path between them. The technical aspects of each technology are discussed with an emphasis on understanding key characteristics of each specification. Technologies including PDC, cdmaOne (IS-95), TDMA (IS-54, IS-136), GSM, GPRS, EDGE, cdma2000 (IS-2000), cdma2000 1xEV-DO (IS-856), and W-CDMA (UMTS FDD) are discussed. Less widely deployed technologies such as cdma2000 1xEV-DV, DECT+, UMTS TDD, and TD-SCDMA are mentioned briefly with limited discussion due to their expected limited use. Available in pdf format.
12. "San Antonio Del Mar: Paragliding Nirvana in Baja California" Paragliding Magazine October 2002 pp. 28-31
    This paper describes a three-day paragliding trip to San Antonio Del Mar located 150 miles south of the border in Baja California. Pilots of all abilities from the Torrey Pines Gliderport in San Diego, CA joined the fun. Everyone had a great time flying along the 14-mile ridge that hugs the Pacific Ocean and provides some of the best flying anywhere. Available in pdf format.
13. "Baja Thermal Clinic 2001" Paragliding Magazine, December 2001 pp. 30-34.
    A first hand account of the 8th annual Baja Thermal Clinic held in La Salina, Mexico during the weekend of Oct 26-28. The paper describes what I saw and learned while at the clinic. The clinic is sponsored each year by Air California Adventure, Inc. and the Torrey Pines Gliderport in San Diego, CA. Available in pdf format.
14. "HDR: The Next Quantum Leap in Speed" Embedded Linux Journal, Jan/Feb 2001, pp. 26-28.
    The goal of anywhere, anytime, high-speed wireless communication will be reached when HDR (High Data Rate) becomes available. Although wireless communication is not new, what is new, is high-speed access. Peak speeds of 2.4 Mbps will be possible. These speeds will make multimedia applications and web surfing, heretofore limited to the desktop, available to the mobile user. This article describes how Linux is playing a critical role in aiding the development and deployment of HDR at Qualcomm, Inc. Available in pdf format.
15. "quakeAPRS" 19th ARRL Digital Communications Conference Proceedings, Miami, Florida, September 2000 pp. 103-108.
    QuakeAPRS provides the APRS network with near real-time earthquake information. It is a perl script run as a cron job on a Linux machine. When the script is executed on the hour and half hour, it connects to the USGS to collect earthquake data. It then converts the information to the standard APRS packet format and sends it via the Internet to APRServe. This allows APRS clients to easily display and track earthquakes. QuakeAPRS has been running 24/7 for nearly a year. This paper describes quakeAPRS, the earthquake object format, and lessons learned from the development of this application. Available in pdf format.
16. "APRSstat: An APRS Network Analysis Tool" 17th ARRL Digital Communications Conference Proceedings, Chicago, Illinois, September 1998, pp. 71-76.
    APRSstat monitors network traffic by connecting to an APRS telnet server and collecting network traffic statistics. The program is intended to run continuously as a background task on a UNIX/Linux system. It collects and saves network data for periods as long as a year. The data gathered by APRSstat is plotted using the companion program APRSgraph, which creates graphs as GIF images allowing them to be integrated into a web page. APRSgraph is executed as a cron job every five minutes providing near real time updates of network usage for daily, weekly, monthly, and yearly periods. Characters per minute is used to measure network traffic. A detailed example of the San Diego, California APRS network is included which is displayed on the author's home web page. A cursory explanation of the software is also included in the paper. APRSstat and APRSgraph were written in perl and use perl modules GD and Chart for creating the graph GIF images. Available in pdf format.
17. "Graphing on the Fly: Generating Real Time Graphs for the Web" Submitted to Linux Journal, March, 1998.
    This paper describes the steps necessary to create real time GIF formatted graphs for web presentation. The software examples provided are written in perl and make use of the GD and Chart perl modules. Included in the paper are installation instructions, examples showing how to use the modules, and a list of resources for further research. Simple examples are provided as well as a more complex example to show the power and flexibility provided by Chart to create informative and easy to understand graphs. Also included is an explanation which illustrates how a web page can automatically update graphs created on the fly. Available in pdf format.
18. "Position Reporting: The Global Positioning System and Linux"Linux Journal, July 1998, pp 46-49.
    In peacetime the Global Positing System (GPS) has given rise to many unique applications and is destined to make its mark in the technological wonders of the world. The Automatic Packet Reporting System (APRS) is an application that uses the GPS to allow amateur radio operators to broadcast latitude, longitude, heading, velocity, and weather to remote receivers. Linux plays an important role in this application. It provides the Gateway between wireless APRS LANs and the Internet. This paper provides an introduction to the GPS, APRS, and describes how Linux is being used to develop a nationwide APRS backbone. Also included is a list of hosts and web sites that Linux users can connect to, to obtain real time position reports. The paper discusses Linux applications aprsmon, aprsd, and PerlAPRS which take advantage of the power of Linux and the Internet to extend the usefulness of the GPS. Available in pdf format.
19. "Mobility and the Internet"IEEE Potentials, April/May 1998, pp 8-10.
    The explosion in demand for mobile computing, both wire and wireless based systems, places demands on the Internet Protocol (IP) that it was not originally intend to support. The protocol assumed that the point at which a computer is connected to the Internet is fixed. If a host is moved to a new network, the current routing protocol will be unable to route the datagrams to the correct destination. Mobile-IP is the new standard intended to address the mobility issue. The current standard developed by the Internet Engineering Task Force (IETF) is described in RFC 2002. This paper provides an introduction to Mobile-IP. It discusses the requirements for mobility on the Internet and how Mobile-IP provides the necessary functionality. Available in pdf format.
20. "Netatalk, Linux and the Macintosh"Linux Journal, January 1998, pp. 26-29.
    Multiple computer platforms on a network are a fact of life. Sun workstations, PCs running Windows 3.x/95/NT/Linux, FreeBSD, and many more, must be able to communicate seemlessly and share data wether they are in an engineering, business, or home environment. Fortunately, with programs like netatalk, getting Apple Macintosh computers and Linux systems to coexist and share resources is easy. The paper describes what netatalk is, what it does, where to get it, how to install it, configure it, and test it. Also included is a short technical description of how netatalk works. Available in pdf format.
21. "PerlAPRS: An Automated Control Application for APRS Networks" 16th ARRL Digital Communications Conference Proceedings, Baltimore, Maryland, October 1997, pp. 141-148.
    PerlAPRS is an application which can monitor both local TNC received APRS packets and remote Internet APRS packets and perform an automated action based on criteria specified by the user. The criteria that PerlAPRS uses is the callsign of the station and its location specified as a Maidenhead Grid Square. Other requirements specified by the user increase functionality of the program in real world applications. The actions executed can be written in any language, but UNIX style shell scripts are ideally suited for this purpose. Scripts can be developed to perform functions such as automatic notification via email as well as logging. PerlAPRS is freely distributed under the GNU licensing agreement. Available in pdf format.
22. "APRS Network Guidelines" 73 Amateur Radio , October 1997, pp. 19-20.
    The Automatic Position Reporting System (APRS) network is significantly different than regular amateur packet networks used for communication. Virtually all amateur packet radio communication uses the connection oriented form of AX.25 which provides error free communication. However, APRS uses the connectionless form of AX.25 which is an unreliable protocol in which lost packets are not detected. Therefore, to help assure reliable communication, operating practices play an important role. This paper provides a list of 20 guidelines that can be used to help insure efficient use of available bandwidth in APRS networks. Available in pdf format.
23. "AX.25 : Analyzing Packet Radio Networks" IEEE Potentials August/September 1997, pp. 14-16.
    This paper describes AX.25 packet radio networks using XNET, a software program specifically designed for this unique type of network analysis. Networks are complex entities most easily explained visually. Through the graphical displays, one can more easily gain an appreciation and understanding of network behavior. XNET runs on UNIX/LINUX systems supporting the Tcl/Tk language. XNET is the result of a Master's degree project requirement completed in May, 1995 at North Central College, Naperville, Illinois. All source code is released under the terms of the GNU General Public License and is available at the author's home page. Available in pdf format.
24. "Position Reporting with APRS" QST June 1997, pp. 60-63.
    The Automatic Packet Reporting System (APRS) allows amateur radio operators to broadcast information from simple position reports containing heading and velocity measurements, to weather reports, and more. This paper is intended as an introduction for the beginner, but special attention is given to address a few of the more esoteric topics of APRS that should be of interest to all users. It provides information on how to set up several types of APRS stations ranging from a simple listen only station to a mobile broadcasting system. Particular attention is given to the APRS network protocol which can be confusing even to the advanced user. Included is an extensive source for obtaining shareware software, and a comprehensive list of APRS related web sites. Available in pdf format.
25. "Using Software Test and Analysis Tools for Test Case Development" February 1997.
    This paper concentrates on the functionality and use of modern software test tool and how they can be used to develop test cases that provide a confidence level for the software testing process. Several of the metrics used to test software including code coverage are discussed in detail. The theory and definitions of the metrics are also provided. Extensive use of examples is included to show actual results for specific test cases. Available in pdf format.
26. "Mobile-IP" February 1997.
    The explosion in demand for mobile computing, both wire and wireless based systems, places demands on the Internet Protocol (IP) that it was not originally intend to support. The protocol assumed that the point at which a computer is connected to the Internet is fixed. If a host is moved to a new network, the current routing protocol will be unable to route the datagrams to the correct destination. Mobile-IP is the new standard intended to address the mobility issue. It is presently under development (Revision 16 is present release) by the Internet Engineering Task Force (IETF). This paper describes the Mobile-IP protocol in theory and as an actual implementation. The theory portion of the paper describes the protocol in detail and reviews the present literature and work in the area. The implementation portion of the paper describes hands-on experience with the installation of a Mobile-IP system. The software is currently available for the Linux operating system and is freely released under the GNU Public License (GPL) agreement. The software was successfully demonstrated at ACM's First International Conference on Mobile Computing (MobiCom `95) held at Berkeley, CA and Nomadic `96 held in Sa Jose, CA. Available in pdf format.
27. "Wireless Digital Communication: An Introduction to the Forward Link" December 1996.
    This paper provides an introduction to wireless digital communication. The challenges facing wireless communication are Herculean due to the hostile air interface. A description of how the codec, vocoder, encoder, interleaver, and modulator elements may be optimized for the wireless medium is provided. Multiple access techniques such as FDMA, TDMA, and CDMA are also discussed. The advantages of spread spectrum over other methods are given particular attention. Several types of spread spectrum techniques such as Direct Sequence, Frequency and Time Hopping are discussed along with the theory behind these methods. Special attention is given to pseudo noise (PN) codes and how they are generated as well as how these codes are used to spread the desired data signal. The discussion is limited to modulation (forward link) of the communication channel rather than demodulation (reverse link). Available in pdf format.
28. "The SSC Low Energy Booster" H.-Ulrich Wienands, R. Parry, et. al. IEEE Press, Piscataway, NJ 1997.
    This book, subtitled "Design and Component Prototype for the First Injector Synchrotron" provides a look at the steps taken toward implementation of the Low Energy Booster (LEB) that was to be built 40 miles south of Dallas, Texas until U.S. Congress halted the Superconducting Super Collider project in October of 1993. The book captures design decisions made for this first injector. I was fortunate enough to be part of this grand project and contributed the section of the book on the Personal Access Safety System. Excerpt from book available in pdf format.
29. "Amateur Radio and Linux," 73 Amateur Radio, February 1997, pp. 10-16.
    This paper is an introduction to Linux, a 32 bit, multi-tasking, multi-user, computer operating system. The paper emphasizes uses of Linux in amateur radio communication and software development. Included is a brief history and description of Linux, a list of amateur radio applications, and numerous sources for further investigation for readers wishing to implement Linux. Available in pdf format.
30. "ISDN: The New Legal Limit," QEX magazine, October, 1996, pp. 11-14.
    Amateur radio operators have always embraced new technology, and in many cases, have been the developers. The new frontier today is the World Wide Web which is affecting the way we communicate and get information. A limitation to the information superhighway is the connection speed. This article describes the Integrated Services Data Network (ISDN), an all digital connection to the Public Switched Telephone Network (PSTN). The paper focuses on ISDN connections to the Internet which provide significantly improved connection speeds over standard analog modems. Included are the author's experiences with special attention given to the costs that one should consider. In addition, a discussion of hardware required, an overview of what ISDN is, and references are provided for further investigation. Available in pdf format.
31. "XNET: A Graphical Look At Amateur Radio Packet Networks," 15th ARRL Digital Communications Conference Proceedings, Seattle Washington, September 1996, pp.64-75.
    This paper describes AX.25 packet networks from a graphical standpoint using XNET, a software program specifically designed for network analysis. Networks are complex entities most easily explained visually. Through the graphical displays, one can more easily gain an appreciation and understanding of a network. It also allows one to see problems and the general behavior of the network. XNET runs on UNIX/LINUX systems supporting the Tcl/Tk language. Available in pdf format.
32. "XNET An X-Windows Based AX.25 Packet Network Analyzer," Master's Project for MSCS degree presented May 24, 1995.
    This Master's project paper describes the development of XNET, a packet network analyzer which collects and displays network information in an X-Windows environment. XNET is written in the Tcl/Tk language, a language optimized for graphical user interface development. The hardware for the project consists of a radio transceiver and a Terminal Node Controller (TNC) which connects to the computer system through a serial port.

    XNET analyzes AX.25 wireless packet networks which predominately operate in the two meter band (144 to 148 MHz). The AX.25 data link layer protocol is a variant of the international standard X.25 protocol. The protocol has been slightly modified to meet the unique requirements of amateur radio packet communication. Unlike wire and optical fiber based networks where the network configuration is relatively stable, wireless networks continually change as nodes are switched on and off. Wireless networks are also more error prone due to the variability of the medium. It is this variability and randomness that makes a network analyzer, such as XNET, so important to the understanding of the network.

    The paper includes an introduction to the Tcl/Tk language and a detailed description of the AX.25 protocol used in wireless packet networks. Also included is an extensive section devoted to the details of the XNET software sufficient for understanding the many design decisions that were made during the development of the program. A description of the hardware used for the system, a complete Operating Manual, and all source code are included as appendices. Available in pdf format.

33. "A High Reliability Oxygen Deficiency Monitoring System," Presented at the Particle Accelerator Conference, Washington D.C. 1993, R. Parry, et. al.
    The escalating use of cryogens at national laboratories in general and accelerators in particular, along with the increased emphasis placed on personnel safety, mandates the development and installation of oxygen monitoring systems to insure personnel safety in the event of a cryogenic leak. Numerous vendors offer oxygen deficiency monitoring systems but fail to provide important features and/or flexibility. This paper describes a unique oxygen monitoring system developed for the Magnet Test Laboratory (MTL) at the Superconducting Super Collider Laboratory (SSCL). Features include: high reliability, oxygen cell redundancy, sensor longevity, simple calibration, multiple trip points, offending sensor audio and visual indication, global alarms for building evacuation, local and remote analog readout, event and analog data logging, EMAIL event notification, phone line voice status system, and multi-drop communications network capability for reduced cable runs. Of particular importance is the distributed topology of the system which allows it to operate in a stand-alone configuration or to communicate with a host computer. This flexibility makes it ideal for small applications such as a small room containing a cryogenic dewar, as well as larger systems which monitor many offices and labs in several buildings. Available in pdf format.
34. "Personnel Electronic Safety Systems," Presented at the Particle Accelerator Conference, Washington D.C. 1993.
    Traditionally safety systems intended for protecting personnel from electrical and radiation hazards at particle accelerator laboratories have made extensive use of electromechanical relays. These systems have the advantage of high reliability and allow the designer to easily implement fail-safe circuits. Relay based systems are also typically simple to design, implement, and test. As systems, such as those presently under development at the Superconducting Super Collider Laboratory (SSCL), increase in size, and the number of monitored points escalates, relay based systems become cumbersome and inadequate. The move toward Programmable Electronic Safety Systems is becoming more widespread and accepted. In developing these systems there are numerous precautions the designer must be concerned with. Designing fail-safe electronic systems with predictable failure states is difficult at best. Redundancy and self-testing are prime examples of features that should be implemented to circumvent and/or detect failures. Programmable systems also require software which is yet another point of failure and a matter of great concern. Therefore the designer must be concerned with both hardware and software failures and build in the means to assure safe operation or shutdown during failures. This paper describes features that should be considered in developing safety systems and describes a system recently installed at the Accelerator Systems String Test (ASST) facility of the SSCL. Available in pdf format.
35. "Cryogenic and Power Testing of a String of 50-mm Aperture Dipole Magnets at the Superconducting Super Collider Laboratory," Presented at the Particle Accelerator Conference Germany 1992. Tom Dombeck, R. Parry et. al.
    This paper is an overview of the Accelerator Systems String Test facility and the success of using it to test prototype Superconducting magnets. The paper describes the numerous systems necessary to bring about the success of the project.
36. "Personnel Access Safety Systems," Proceedings of the Industrial Computing Conference, Vol. 2, p 437, ISA 1992 Paper #92-0467.
    This paper describes the method and system used to control personnel accesses into hazardous areas at the Superconducting Super Collider. Hazards encountered are electrical (high voltage and high current), radiation (ionizing), cryogenic fluids (liquid helium and nitrogen), flammable gases, and ultra high magnetic fields. Although these are a diverse group of hazards, virtually all can be mitigated by controlling accesses into the hazardous enclosures. The Personnel Access Safety System (PASS) is used for this purpose. The system is comprised of dual redundant Programmable Logic Controllers (PLC) using 1oo2 voting (either system can bring the system down to a safe state). Numerous safety related hardware and software features have been built into this system to assure high reliability and availability. Available in pdf format.
37. "OS-9 Meets High Energy Physics," Pipelines Volume 6 Number 1 Winter 1991, p. 4.
    This paper describes the computer monitoring systems used at the Fermi National Accelerator in Batavia, Illinois. The computer system uses OS9, a real time operating system similar to UNIX. OS9 was used primarily due to the need for a real-time OS. The paper includes a description of the computer system and the systems that it monitors.
38. A Super Synthesizer Microcomputing August 1982," p. 82.
    This article describes a high quality speech synthesizer which uses the National Semiconductor Digitalker¨ speech chips. Space is provided for two ROM sets which contain a total of 275 words. An on-board FIFO buffer is provided to free the processor for other tasks while speech is produced. Music and sound effects are possible by way of an 8 bit D/A converter. Complete construction details are included. The synthesizer is available as a board only, in kit form, or assembled and tested.
39. "The Infamous Traveling Salesman Problem: A Practical Approach," BYTE July 1981, p. 252.
    Among mathematical problems, there is a group of problems that are referred to as NP-Complete (Non-deterministic Polynomial), the Traveling Salesman Problem is such a problem. This article describes a computer program which can calculate the shortest path through a series of points of which each point is to be visited only once. The algorithm makes heavy use of decision tree pruning to drastically reduce the execution time. Several examples are given to illustrate the power of the program. NP-complete problems are not just an academic curiosity but have real world significance. This class of problem has become more widely studied since the advent of computer security and the widespread use of networks. The paper includes a computer program that drastically reduces the time required to solve a given problem, it is not a complete solution. However, at this writing there is no solution to solving such problems easily, they all require vast computer power to solve even small problems.
40. "An English Text Analysis and Concordance Program," Kilobaud Microcomputing June 1981, p. 58.
    This article describes a program that is used to analyze ordinary English text. The input to the program may be either from a terminal or text file. The output displays the number of lines, sentences, words, and syllables; as well as, the average word and sentence length. In addition, a readability score of the text is given as a grade level. The user may also select to have the program construct a concordance table. A complete computer program is included as well as several examples.
41. "Math Can Be Fun," Kilobaud Microcomputing April 1981 p. 128.
    This article describes a program that turns a microcomputer into a teaching machine. The program is geared to teaching young children (i.e., grades 1-5) the four basic arithmetic functions (addition, subtraction, multiplication, and division).
42. "Hard-Hat Management: Two On-Site Tools," Interface Age February 1981, P.70.
    This article describes the Critical Path Method (CPM) and the Performance Evaluation and Review Technique (PERT) of project management. A computer program is provided to remove the tedious calculations inherent in CPM and PERT. The CPM calculations are computed using a conventional algorithm, while the PERT calculation is performed using simulation. Several examples are included to show how the program is used.
43. "Computerized Security and Status System," Kilobaud Microcomputing November 1980, P. 30.
    The article describes a computer controlled home security control and montoring system. The program is written in 6800 assembly language. Inputs to the system are: a self-test switch, a telephone, doorbells, furnace, motion detector, and windows. All events such as receiving a telephone call or the cycling of the furnace are displayed on a printer. Some events such as breaking a window cause a siren to be actuated. Appended to each event is the time and date.
44. "Simple Linear Regressions: A Forecasting Tool," Interface Age August 1980, p. 42.
    This article describes the use of linear regression as a means of predicting future data based on historical information. Several applications are given to indicate how to use the program and to show typical uses of linear regression. A complete computer program is included. The program not only calculates the least squares line, but can also plot the line and input data on a graph. Other features allow the users to store and retrieve data files so that they can be used at a later date.
45. "Function Plotter," Interface Age December 1980, p. 36.
    This article describes a computer program which is capable of plotting two user defined functions. The program can plot either of the functions separately, or both simultaneously. It can plot the function in any or all of the four quadrants of a graph. Automatic scaling of the Y axis assures that the graph will be easy to read. In addition, the user may specify the lower and upper limits of the X axis as well as the X increment. This feature gives one complete freedom in specifying the resolution of the graph.
46. "Point Plotter and Statistical Analysis Package," Interface Age November 1980, P.34.
    This article describes a computer program which is capable of automatically plotting X and Y data pairs on a graph. Points may be plotted in any or all four quadrants of the graph. Automatic scaling of the Y axis assures that the graph will be easy to read. Once the data has been inserted, the user need only supply the range of the X and the X increment in order to obtain a neat and accurate graph. The program also allows the user to store and retrieve data files so that they can be used at a later date. Some statistics are calculated to aid the user in describing the data and drawing inferences.
47. "Software Clock for the 6800," Kilobaud Microcomputing, January 1980, p. 150.
    This article describes a program that allows the user to append both the time and date to any event. The program uses conventional 60 Hz commercial power for the timebase and services the interrupts through a Motorola 6820 Peripheral Interface Adapter (PIA) integrated circuit. The program is written in 6800 assembler.
48. "Blockbuster RTTY Article!," 73 Amateur Radio, November 1978, p. 254 and RTTY Journal May/June, July/August, 1980.
    This article describes a selective calling system (SELCAL) and an answer back system (W-R-U) to be used by RTTY enthusiasts interested in autostart operation. The circuit is fabricated on two printed circuit boards.
49. "So You Want to Get Into RTTY," 73 Amateur Radio, September 1977, p. 28.
    This article is an introduction to the world of amateur radioteletype (RTTY). It describes the basic techniques and concepts important to understand in amateur radioteletype. An annotated bibliography is included to help those interested in further understanding this facet of amateur radio. A glossary is also included for reference. This paper was submitted as a contestant in a writing contest and won first prize.
50. "RTTY CRT Tuning Indicator," 73 Amateur Radio, September 1977, p. 118
    This article describes a circuit design that enables to one easily tune an incoming RTTY signal using a CRT rather than the more common tuning meter.
51. "RTTY RKB-1 Revisited," 73 Amateur Radio, September 1977, p. 158.
    The article describes a circuit that will automatically perform the proper RTTY end-of-line sequence when a single "return" key is depressed. The circuit is a modification to a commercial electronic keyboard manufactured by HAL Inc of Champaign, Illinois.
52. "The Ultimate Speech Synthesizer: Unlimited Speech, Music, and Sound Effects," unpublished paper
    This paper describes a speech, music, and sound effects synthesizer. Speech synthesis is accomplished using the VOTRAX SC-01 integrated circuit which reproduces 64 phonemes and allows for unlimited speech. The circuit incorporates a FIFO buffer which frees the processor for other tasks while speech is reproduced. Music and sound effects are synthesized using an 8 bit D/A converter. Included are complete construction plans, example programs, and schematics. Also offered are the printer circuit board only, a kit, or the entire unit assembled and tested.
53. "Pascal Meets HI-LO," accepted unpublished.
    This article describe a guessing game called HI-LO. The object of the game is to guess a number that is picked randomly by the computer. The program is well documented PASCAL program. The program is intended as a PASCAL tutorial.
54. "The Decibel: The Theory Behind It and a BASIC Program To Calculate It," Accepted by 73 Amateur Radio.
    This article describes the theory, calculation, and use of the decibel. Also included is a computer program which calculates the decibel for several applications. Several examples are included to help illustrate the power and use of the program.
55. "The Ultimate Music Synthesizer: 4 Voices, 4 Channels, 4 Instruments," Accepted by 73 Amateur Radio.
    This paper describes an extremely flexible music synthesizer. The hardware consists of a synthesizer made to interface with the SS-50 bus. Each board has two D/A channels with a low pass filter and power amplifier. With two such boards, each of the four voices may be reproduced through its own channel. The software consists of two BASIC programs and a 6809 assembly language program.. Inlcuded are complete construction plans, examples, programs, and schematics. The hardware is available as a bare board, as a kit, or assembled and tested. The software is also available on disk.
56. "An Evaluation of the Motorola MEK6800D2 Evaluation Kit," Accepted by 73 Amateur Radio.
    The paper evaluates the Motorola MEK6800D2 single board microcomputer. Emphasis is placed on the ease of learning microcomputer concepts using an evaluation kit.
57. "A Radioteletype Program for the M6800," Accepted by 73 Amateur Radio.
    This article describes a very flexible program for amateur radio operators interested in communicating via RTTY. The program simulates and/or includes: a real-time clock, a SELCAL (selective calling system), a W-R-U (answer back system, who are you), a regenerative repeater, a character buffer, a micro text editor, and a control system for the radio station.