Encyclopedia of Computer Science and Technology

shareware and freeware 427Along with the work of Alan Turing and John von Neumann(see Turing, Alan and von Neumann John), Shannon’slogical analysis of switching circuits would becomeessential to the inventors who would build the first digitalcomputers in just a few years. (Demonstrating the breadth ofhis interests, Shannon’s Ph.D. thesis would be in an entirelydifferent application—the algebraic analysis of problems ingenetics.)In 1941, Shannon joined Bell Laboratories, perhapsAmerica’s foremost industrial research organization. Theworld’s largest phone company had become increasinglyconcerned with how to “scale up” the burgeoning telephonesystem and still ensure reliability. The coming of waralso highlighted the importance of cryptography—securingone’s own transmissions while finding ways to breakopponents’ codes. Shannon’s existing interests in both datatransmission and cryptography neatly dovetailed with theseneeds.Shannon’s paper titled “A Mathematical Theory of Cryptography”would be published after the war. But Shannon’smost lasting contribution would be to the fundamental theoryof communication. His formulation would explain whathappens when information is transmitted from a sender toa receiver—in particular, how the reliability of such transmissioncould be analyzed (see information theory).Shannon’s 1948 paper, “A Mathematical Theory ofCommunication” was published in The Bell System TechnicalJournal. Shannon identified the fundamental unit ofinformation (the binary digit, or “bit” that would becomefamiliar to computer users). He showed how to measure theredundancy (duplication) within a stream of data in relationto the transmitting channel’s capacity, or bandwidth.Finally, he showed methods that could be used to automaticallyfind and fix errors in the transmission. In essence,Shannon founded modern information theory, which wouldbecome vital for technologies as diverse as computer networks,broadcasting, data compression, and data storage onmedia such as disks and CDs.One of the unique strengths of Bell Labs is that it didnot limit its researchers to topics that were directly relatedto telephone systems or even data transmission in general.Like Alan Turing, Shannon became interested after the warin the question of whether computers could be taught toperform tasks that are believed to require true intelligence(see artificial intelligence). He developed algorithmsto enable a computer to play chess and published an articleon computer chess in Scientific American in 1950. He alsobecame interested in other aspects of machine learning, andin 1952 he demonstrated a mechanical “mouse” that couldsolve mazes with the aid of a circuit of electrical relays.The mid-1950s would prove to be a very fertile intellectualperiod for AI research. In 1956, Shannon and AIpioneer John McCarthy (see McCarthy, John) put out acollection of papers titled “Automata Studies.” The volumeincluded contributions by two other seminal thinkers, Johnvon Neumann and Marvin Minsky (see Minsky, Marvin).Although he continued to do research, by the late 1950sShannon had changed his emphasis to teaching. As DonnerProfessor of Science at MIT (1958–1978) his lecturesinspired a new generation of AI researchers. During thesame period Shannon also explored the social impact ofautomation and computer technology as a Fellow at theCenter for the Study of Behavioral Sciences in Palo Alto,California.Shannon received numerous prestigious awards, includingthe IEEE Medal of Honor and the National Medal ofTechnology (both in 1966). Shannon died on February 26,2001, in Murray Hill, New Jersey.Further ReadingShannon, Claude Elwood. “A Chess-Playing Machine.” ScientificAmerican, February 1950, 48–51.———. Collected Papers. Ed. N. J. A. Sloane and Aaron D. Wyner.New York: IEEE Press, 1993.———. “A Mathematical Theory of Communication.” Bell SystemTechnical Journal 27; July and October, 1948, 379–423, 623–656. Available online. URL: http://plan9.bell-labs.com/cm/ms/what/shannonday/shannon1948.pdf. Accessed August 21,2007.Waldrop, M. Mitchell. “Claude Shannon: Reluctant Father of theDigital Age.” Technology Review, July/Aug. 2001. Available online.URL: http://www.technologyreview.com/Infotech/12505/.Accessed August 21, 2007.shareware and freewareThe early users of personal computers generally had considerabletechnical skill and a desire to write their ownprograms. This was partly by necessity: If one wanted toget an Apple, Atari, Commodore, or Radio Shack machineto perform some particular task, chances were one wouldhave to write the software oneself. Commercial softwarewas scarce and relatively expensive. However, given enoughtime, it was possible for hobbyists to write programs usingthe machine’s built-in BASIC language or (with more effort)assembly language.Programs such as utilities and games were often freelyshared at gatherings of PC enthusiasts (see user groups).Many talented amateur programmers considered trying toturn their avocation into a business. However, a utility toprovide better file listings or a colorful graphics programthat creates kaleidoscopic images was unlikely to interestthe commercial software companies who developed largeprograms in-house for marketing primarily to business.In 1982, Andrew Fuegelman created a program calledPC-Talk. This program provided a better way for users withmodems to connect to the many bulletin board systemsthat were starting to spring up. Fluegelman was familiarwith the common practice of public radio and TV broadcastersof soliciting pledge payments to help support their“free” service. He decided to do something similar with hisprogram. He distributed it to many bulletin boards, whereusers could download it for free. However, he asked userswho liked the program and wanted to continue to use it topay him $25.Fluegelman dubbed his method of software distribution“freeware” (because it cost nothing to try out the program).Other programmers began to use the same method withtheir own software. This included Jim Knopf, author of thePC-File database program, and Bob Wallace, who offered