Encyclopedia of Computer Science and Technology

144 device driverOne Laptop per ChildWhile the conventional view of technological developmentstresses the importance of infrastructure and skills, somevisionary educational activists are suggesting a way to“jump-start” the information economy in poor and developingcountries. They note that despite the potential ofwireless technology, adequate computing power for joiningthe world network has simply been too expensive for allbut the elite in developing countries. (A $400 no-frills PCcosts more than the annual per capita income of Haiti, forexample.)In response, MIT computer scientists (see Mit MediaLab and Negroponte, Nicholas) have started an initiativecalled One Laptop Per Child. Their machine (introduced asa prototype in 2005) includes the following features:• very low power consumption (2–3 watts)• lower and higher power modes (the latter, for example,can provide backlighting for the screen when anexternal power source is available)• ability to use a variety of batteries or an externalpower source, including a hand-powered generator• built-in wireless networking• tough construction, including a water-resistant membranekeyboard• flash memory instead of a hard drive or CD-ROM• built-in color camera, microphone, and stereo speakers• open-source Linux operating system and other software,including programming languages especiallyuseful for learnersThe computer is intended ultimately to cost no more than$100 per unit, and is to be distributed through participatinggovernments. Countries that have made at least tentativecommitments to the project as of 2007 include Argentina,Cambodia, Costa Rica, Dominican Republic, Egypt, Greece,Libya, Nigeria, Pakistan, Peru, Rwanda, Tunisia, Uruguay,and, in the United States, the states of Massachusetts andMaine.The underlying philosophy of the project is based on“constructivist learning,” the idea that children can learnpowerful ideas through using suitable interactive systems(see logo and Papert, Seymour). In a way it is intendedto be a sort of lever to create a generation with the skills tofunction in the 21st-century information economy, withoutre-creating the cumbersome industrial-style educationalsystems of the previous 200 years.Although, generally, some well received critics are concernedabout the environmental impact of producing (andeventually disposing of) millions more computers, whileothers (including some officials in developing countries)believe the money for providing computers to childrenshould be used instead for more urgent needs such as cleanwater, public health, and basic school supplies.Whether using top-down or bottom-up approaches, theweb of connection, communication, and information continuesits rapid though uneven spread around the world.However, as new technologies continue to emerge in thedeveloped world, the position of technological “have-nots”may worsen if effective education and access programs arenot developed.Further ReadingDesai, Meghnad, et al. “Measuring the Technological Achievementof Nations and the Capacity to Participate in the NetworkAge.” Journal of Human Development 3 (2002): 95–122.Available online. URL: http://unpan1.un.org/intradoc/groups/public/documents/apcity/unpan014340.pdf. Accessed September11, 2007.One Laptop per Child. Available online. URL: http://laptop.org/vision/index.shtml. Accessed September 11, 2007.Wilson, Ernest J., III. The Information Revolution and DevelopingCountries. Cambridge, Mass.: MIT Press, 2004.Wireless Internet Institute. The Wireless Internet Opportunity forDeveloping Countries. Boston, Mass.: World Times, 2003.device driverA fundamental problem in computer design is the controlof devices such as disk drives and printers. Each deviceis designed to respond to a particular set of control commandssent as patterns of binary values through the portto which the device is connected. For example, a printerwill respond to a “new page” command by skipping linesto the end of the current page and moving the print headto the start of the next page, taking margin settings intoaccount. The problem is this: When an applications programsuch as a word processor needs to print a document,how should the necessary commands be provided to theprinter? If every application program has to include theappropriate set of commands for each device that might bein use, programs will be bloated and much developmenteffort will be required for supporting devices rather thanextending the functionality of the product itself. Instead,the manufacturers of printers and other devices such asscanners and graphics tablets typically provide a programcalled a driver. (A version of the driver is created for eachmajor operating system in use.) The driver serves as theintermediary between the application, the operating systemand the low-level device control system. It is sometimesuseful to have drivers in the form of continually runningprograms that monitor the status of a device and wait forcommands (see demon).Modern operating systems such as Microsoft Windowstypically take responsibility for services such as printingdocuments. When a printer is installed, its driver programis also installed in Windows. When the application programrequests to print a document, Windows’s print systemaccesses the driver. The driver turns the operating system’s“generic” commands into the specific hardware controlcommands needed for the device.While the use of drivers simplifies things for both programdevelopers and users, there remains the need for usersto occasionally update drivers because of an upgrade eitherin the operating system or in the support for device capabilities.Both Windows and the Macintosh operating system