Encyclopedia of Computer Science and Technology

200 flowchartused to hold data. The surface is divided into concentrictracks that are in turn divided into sectors. (For more ondisk organization, see hard drive.) The heads are preciselypositioned to the required track/sector location using steppermotors under control of the disk driver. The data capacityof a disk depends on how densely tracks can be writtenon it. Today’s 3.5-inch diskettes typically hold 1.44 MB ofdata.In recent years, drive technology has advanced so thatmany more tracks can be precisely written in the sameamount of surface. The result is found in products such asthe popular Zip disks, which can hold 100 MB or even 250MB, making them comparable in capacity and speed witholder, smaller hard drives.Since the late 1990s, the traditional floppy disk has becomeless relevant for most users. With more computers connectedto networks, the use of network copying commands or e-mailattachments has made it less necessary to exchange files viafloppy, a practice dubbed “sneaker-net.” When data needs tobe backed up or archived, the high-capacity USB drive, tape,or writable CD is a more practical alternative to low-capacityfloppies. (See backup and archive systems.) With its iMacline, Apple actually discontinued including a floppy drive asstandard equipment. In PC-compatible laptops, a floppy driveis often available as a plug-in module that can be alternatedwith other devices. Desktop systems still sometimes comewith a single 3.5-inch drive.Further ReadingWhite, Ron. How Computers Work. 8th ed. Indianapolis: Que,2005.flowchartA flowchart is a diagram showing the “flow” or progress ofoperations in a computer program. Flowcharting was oneof the earliest aids to program design and documentation,and a plastic template with standard flowcharting symbolswas a common programming accessory. Today CASE (computer-aidedsoftware engineering) systems often includeutilities that can automatically generate flowcharts basedon the control structures and procedure calls found in theprogram code (see case).The standard flowchart symbols include blocks of variousshapes that represent input/output, data processing,sorting and collating, and so on. Lines with arrows indicatethe flow of data from one stage or process to the next. Adiamond-shaped symbol indicates a decision to be madeby the program. If the decision is an “if” (see branchingstatements) separate lines branch off to the alternatives.If the decision involves repeated testing (see loop), the linereturns back to the decision point while another line indicatesthe continuation of processing after the loop exits.Devices such as printers and disk drives have their ownsymbols with lines indicating the flow of data to or fromthe device.Complex software systems can employ several levels offlowcharts. For example, a particular routine within a programmight have its own flowchart. The routine as a wholeA flowchart uses a set of simple symbols to describe the stepsinvolved in a data processing operation. The parallelograms indicatean input/output operation (such as reading or writing a file).The “decision diamonds” have yes and no branches depending onthe result of a test or comparison.would then appear as a symbol in a higher-level flowchartrepresenting the program as a whole. Finally, a system chartmight show each program that is run as part of an overalldata processing system.While still useful, flowcharting is often supplemented byother techniques for program representation (see pseudocode).Also, modern program design tends to shift theemphasis from charting the flow of processing to elucidatingthe properties and relationships of objects (see objectorientedprogramming).Further ReadingBoillot, M. H., G. M. Gleason, and L. W. Horn. Essentials of Flowcharting.New York: WCB/McGraw-Hill, 1995.fontIn computing, a font refers to a typeface that has a distinctiveappearance and style. In most word processing, desktoppublishing, and other programs the user can select thepoint size at which the font is to be displayed and printed(in traditional typography each point size would be consideredto be a separate font). Operating systems such as Win-