Encyclopedia of Computer Science and Technology

hexadecimal system 225If not a programmer, the user of a mainframe program wasprobably at least a well-trained operator who could workwith the aid of a brief summary or notes provided by theprogrammer. However, with the beginnings of office automationin the 1970s and the growing use of desktop computersin office, home, and school in the 1980s, increasinglycomplex programs were being put in the hands of userswho often had only minimal computer training (see computerliteracy).While programs often came with one or more tutorialor reference manuals, designers realized that offering helpthrough the program itself would have some clear advantages.First, the user would not have to switch attention fromthe computer screen to look things up in a manual. Second,the help system could be programmed to not only provideinformation, but also to help the user find the informationneeded in a given situation. For example, related topicscould be linked together and a searchable index provided.ImplementationPrograms running under the text-based MS-DOS of the1980s tended to have only rudimentary help screens (ofteninvoked by pressing the F1 key). Generally, these were limitedto brief summaries of commands and associated keycombinations. However, with the growing use of MicrosoftWindows (and the similar Macintosh interface), a morecomplete and versatile help system was possible. Since thesesystems allowed multiple windows to be displayed on thescreen, the user could consult help information while stillseeing the program’s main screen. This allowed for trying arecommended procedure and observing the results.Windows and Macintosh help systems also featuredhighlighted links in the text that could be used to jump torelated topics (see hypertext and hypermedia). A topicword can also be typed into an index box, bringing up anymatching topics. If all else fails, the entire help file could beindexed so that any word could be used to find matchingtopics.More recent Windows programs also include wizards. Awizard is a step-by-step procedure for accomplishing a particulartask. For example, if a Microsoft Word user want tolearn how to format text into multiple columns, the help systemcan offer a wizard that takes the user through the procedureof specifying the number of columns, column size, andso on. The steps can even be applied directly to the documentwith the wizard “driving” the program accordingly.Recently, many programs have implemented their helpin the form of Web pages, stored either on the user’s computeror at the vendor’s Web site (see html). HTML has theadvantage that it is now a nearly universal format that canbe used on a variety of platforms and (if hosted on a Website) the help can be continually improved and updated.(Microsoft’s latest version of HTML Help has supplanted itsoriginal WinHelp, which is no longer supported by Vista.)A variety of shareware and commercial help authoringsystems such as RoboHelp are available to help developerscreate help in Windows or HTML format. UNIX systems,which have always included an on-line manual, now typicallyoffer HTML-based help as well.With printed documentation being increasinglyeschewed for cost-cutting reasons, users of many programstoday must depend on the help system as well as on on-linedocuments (such as PDF files) and Web-based support.Further ReadingHackos, JoAnn T., and Dawn M. Steven. Standards for Online Communication:Publishing Information for the Internet/World WideWeb/Help Systems/Corporate Intranets. New York: Wiley, 1997.Heng, Christopher. “Free Help Authoring, Manual and DocumentationWriting Tools.” Available online. URL: http://www.thefreecountry.com/programming/helpauthoring.shtml.Accessed August 6, 2007.“Microsoft HTML Help 1.4 SDK.” Available online. URL: http://msdn2.microsoft.com/en-us/library/ms670169.aspx. AccessedAugust 6, 2007.Weber, Jean Hollis. Is the Help Helpful? How to Create Online HelpThat Meets Your Users’ Needs. Whitefish Bay, Wisc.: HentzenwerkePublishing, 2004.hexadecimal systemThe base 16 or hexadecimal system is a natural way to representthe binary data stored in a computer. It is more compactthan binary because four binary digits can be replacedby a single “hex” digit.The following table gives the corresponding decimal,binary, and hex values from 0 to 15:Decimal Binary Hex0 0 01 0001 12 0010 23 0011 34 0100 45 0101 56 0110 67 0111 78 1000 89 1001 910 1010 A11 1011 B12 1100 C13 1101 D14 1110 E15 1111 FNote that decimal and hex digits are the same from 0 to9, but hex uses the letters A–F to represent the digits correspondingto decimal 10–15. The system extends to highernumbers using increasing powers of 16, just as decimaluses powers of 10: For example, hex FF represents binary11111111 or decimal 255. Many of the apparently arbitrarynumbers encountered in programming can be better understoodif one realizes that they correspond to convenientgroupings of bits: FF is eight bits, sufficient to hold a singlecharacter (see characters and strings). In low-level programmingmemory addresses are also usually given in hex(see assembler).