Chapter 2: Handheld DevicesThere are three essential types of handheld devices: mobile telephone handsets, pagers, and PDAs. Though many newer devices blur this distinction, design principles will be dictated by one or more of these formats. All handheld devices share two common challenges: small display and problematic data input. Handheld phones generally support voice communication, contact management and data connectivity via WAP or i-mode. Data is entered on a standard twelve-key keypad, with the help of various soft keys. PDAs customarily support address books, calendars, to-do lists, email management, and note taking. Data is entered via styli or through desktop synchronization. Pagers support one- or two-way email, and now often feature QWERTY keypads. Adherence to distinct rules governing the design of labeled buttons, soft-keys, silk-screened buttons, keypads, roller wheels, rocker controls, and touch screens all aid in promoting optimum usability. Though various data entry systems have their pros and cons, no system has yet been developed that rivals the efficiency and ease of use of the standard desktop keyboard and mouse. Handheld displays are also problematic. Telephones in particular often have severely confined display areas, and when working with them one must design applications with the most restrictive cases in mind. Displays should be limited to 4x12 characters, including soft keys, and blank lines should never be used, as they confuse users. Aside for the issues
regarding input and displays a myriad of competing hardware and protocol
standards pose challenges to usable handheld devices. Expansion options
(hooking up to cameras, scanners, etc.) and connectivity (transferring
information between devices) provide
further usability challenges. The currently balkanized world of
competing connectivity standards and incompatible operating systems
precludes organized and rational development of industry-wide norms. In
particular, WAP, the Wireless Application Protocol, has suffered a rocky
debut, due to reasons as diverse as poor implementation and questionable
marketing decisions. Despite its stormy early tenure, however, WAP
appears to be here to stay. Chapter 2 – Handheld Devices covers:
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