Encyclopedia of Computer Science and Technology

DVR 163DSL uses special modems to convert between computer data and signals that can travel over ordinary phone lines. This technology is widelyused to provide broadband Internet access.infrastructure has created considerable competition. Thusa cable provider can now offer telephone service via theInternet (see voip) at the same time a phone provider usingDSL can offer movies and television programming streamedover the network. The fact that in many locations DSL andcable providers are in competition can result in lower ratesor more attractive “bundles” of services for consumers.On average, cable modem speeds are somewhat fasterthan DSL; however, cable speeds can degrade as more usersare added to a circuit. Although both services have had theirshare of glitches, they now both tend to be quite reliable.Further ReadingGolden, Philip, Herve Dedieu, and Krista S. Jacobsen, eds. Implementationand Applications of DSL Technology. Boca Raton,Fla.: CRC Press, 2007.Mitchell, Bradley. “DSL vs. Cable: Modem Comparison.” Availableonline. URL:http://compnetworking.about.com/od/dslvscablemodem/a/dslcablecompare.htm. Accessed September16, 2007.Reynolds, Janice. A Practical Guide to DSL: High-Speed Connectionsfor Local Loop and Network. New York: CMP Books, 2001.Smith, Roderick W. Broadband Internet Connections: A User’s Guideto DSL and Cable. Upper Saddle River, N.J.: Addison-WesleyProfessional, 2007.DTP See desktop publishing.DVR (digital video recording)A digital video recorder (DVR) records digital televisionbroadcasts and stores them on a disk (see hard disk andcd-rom and dvd-rom). DVRs first appeared as commercialproducts in 1999 in Replay TV and TiVo, the latter becomingthe most successful player in the field.A DVR works with digital signals and discs rather thantape used by the video cassette recorders (VCRs) that hadbecome popular starting in the 1980s. The digital recorderhas several advantages over tape:• much larger capacity, limited only by hard drive size• instant (random) access to any recorded programmingwithout having to go forward or backward through atape• the ability to “time shift” within a live broadcast,including pausing and instant replay• the ability to skip over commercials• digital special effectsDVR and Integrated EntertainmentBesides what it can do with the program itself, the otherbig advantage of DVR technology stems from the fact thatit produces digital data in a standard format (usually an