Active-Matrix Display: This display type provides a separately addressable transistor for each picture element (pixel), producing the highest quality image. It is also the most expensive of the display alternatives. Also see Passive-Matrix Display. [Top]

Applications: The capabilities of a PDA are provided by applications software that is either provided with the purchase of the PDA, acquired separately or developed as a custom application. Major application categories include: Personal Information Management(PIM), communications and exchanging data with desktop applications software including word processing and graphic presentation programs. [Top]

Battery Options: PDAs use either standard throw-away alkaline batteries or custom rechargeable batteries. Some rechargeable PDAs have removable batteries so the user can carry multiple batteries to extend work time. An adapter that allows the PDA to run from an electrical outlet is often included or available as an option. [Top]

Backlit Display: A fluorescent panel behind the screen on most PDAs illuminates the image. This supports use of the PDA in low light conditions and makes the screen more readable in bright sunlight. Backlighting reduces battery (or battery charge) life. Some PDAs allow the backlighting to be turned off when not needed to extend battery life. Some "backlit" screens are more accurately described as "sidelit" since the display is illuminated from the sides. Also see Reflective Display. [Top]

Bluetooth: An emerging short-range (10 meters or 33 feet) wireless networking standard that allows PDAs to communicate with other PDAs, desktop/notebook PCs, bluetooth-enabled cell phones and peripheral devices such as printers. A faster competitor to Infrared (IrDA)-based data interchange. [Top]

Body Size: See Form Factor. [Top]

Built-in Applications: PDAs implement some of their applications in flash ROM, while others (provided free by the manufacturer or purchased from the manufacturer or a third party suppier on a CD that you will read with a PC then download to the PDA) are stored in RAM or memory provided by an expansion device. [Top]

Color Depth: Low cost (and low battery power consumption) PDAs usually incorporate a monochrome (four or sixteen grayscale shades) display. The number of colors available on color displays is 256, 4096 or 65,536. Systems that display more colors render photographic images more accurately. Display quality is also influenced by whether the PDA offers a passive or active matrix display and whether the display is backlit. [Top]

Communications: PDA communications are either wired (using a modem or LAN interface) or wireless and generally involve a connection to either a Local Area Network (LAN) or to the Internet to support communications applications such as e-mail, instant messaging or Web access. Some PDA models include a built-in wireless networking interface that can support either wireless LAN or Internet access. With most PDAs, an expansion slot of some type will be required to install add-on communications interface hardware. [Top]

Communications -- Instant Messaging: Instant messaging represents a "live" text-based conversation among two or more parties. PDAs could support this application with wired or wireless network connections. [Top]

Communications -- LAN Access: Direct access to an organization's Local Area Network (LAN) from a PDA could be provided by a wired connection through an expansion module or docking station or through a wireless connection. The connection could be used for any of the communications applications or to synchronize LAN data with the PDA. [Top]

Communications -- e-mail access: PDAs generally allow e-mail to be downloaded from a desktop PC (see synchronizing PDAs...) so you can read them and prepare responses. With a built-in or add-on modem and subscription to an Internet Service Provider (ISP)'s e-mail service, permits sending and receiving e-mail directly from the PDA. Wireless LAN's provide another mechanism for direct e-mail support for PDAs. [Top]

Communications -- Web Access: PDA Web access requires connection to the Internet through a modem, wireless LAN or conventional LAN connection. The small display size of PDAs complicates rendering of complex Web pages. Most PDA-based browsers support scrolling to allow viewing of high resolution pages. Some Web sites provide special output reformatted for small screens (web clipping) and there are server-based programs (implemented by Internet Service Providers) that attempt to reformat pages on the fly. There is at least one browser from Opera that does reformatting on the browser after receiving the Web page. [Top]

Central Processing Unit (CPU): In a PDA, the CPU is represented by the microprocessor. Many different specific microprocessor brands and models are employed in PDAs. The primary performance parameter for the microprocessor is the clock speed measured in MegaHerz (Mhz) that stands for millions of cycles per second. Higher clock speeds imply faster processing of programs, important for computationally intensive tasks such graphically or mathematically-oriented design work. PDA microprocessors tend to be much less powerful than those employed in desktop or notebook PCs because of the restrictions imposed by the small size and limited battery power of handhelds and the less-demanding nature of typical PDA applications software. [Top]

Cradle: See Docking Station/Cradle. [Top]

Display: PDAs use touch-sensitive LCD (liquid crystal display) panels for dynamic display of text and graphics and to capture input from a stylus. Important performance parameters for PDA displays include the screen size, maximum resolution, number of colors (color depth), display type (passive or active-matrix) and availability of backlighting. The image is produced by lighting up small dots called pixels (a contraction of picture elements) in appropriate colors or shades of gray to render text or graphics. The pixels are arranged in rows, and the maximum screen resolution is the number of pixels in each row times the number of rows: 240 x 320 means there are 240 pixels in each row and 320 rows on the screen. More pixels produce a sharper, more detailed image. Typical PDA resolutions are 160 x 160, common on devices supported by the Palm OS, and 240 x 320, common on devices supported by the Pocket PC OS. Other (generally higher) resolutions are available, particularly on newer models, so the manufacturers' specifications should be examined for any PDA under purchase consideration. [Top]

Docking Station/Cradle: Some PDAs include (or provide as an extra cost option) a docking station or "cradle" into which the PDA is plugged. These devices may provide for any or all of the following: supplying non-battery power to the PDA to operate the device and/or recharge its battery, connecting the PDA to a desktop computer to synchronize data, and support for the use of expansion peripheral devices. For some PDA models, accessory cables may be available that eliminate the need for a cradle to recharge batteries or synchronize data. [Top]

Expansion: Many hardware accessories are available for PDAs to extend their utility. Examples include expansion memory, communication devices (including modems and wired or wireless network connectivity), MP3 players, digital cameras and Global Positioning Systems (GPS) for navigation. If not incorporated into the basic PDA, each of these hardware devices has to be supported by an electronic expansion interface that is part of the PDA or incorporated in an docking cradle. Example interfaces include compact flash, memory stick, PC card, Springboard, secure digital, smart media and flash ROM. A specific PDA model could provide multiple expansion interfaces, but no PDA supports all of them: in selecting a PDA the buyer must make sure desired accessories are available for the selected model's interfaces. [Top]

Expansion -- Compact Flash (CF): A variation of the PC card miniaturized to be more suitable for use in PDAs than notebook computers. Support both data storage and other hardware expansion and usually provided on Pocket PC PDAs. [Top]

Expansion -- Memory Stick: A Sony-specific memory card primarily used for data storage. [Top]

Expansion -- PC (PCMCIA): These are relatively large interface cards used primarily in notebook computers. When supported by the PDA (probably through a docking cradle or other attached interface adapter), may allow use of notebook computer peripherals with a PDA. [Top]

Expansion -- Springboard: Available on the Visor Handspring models of Palm OS compatible PDAs. Example applications include memory expansion, games, communications, maps and GPS navigation. [Top]

Expansion -- Secure Digital (SD): Used for data storage or to load external data such as maps or other guides. [Top]

Expansion -- Smart Media: A very small card used for data storage. Used in some digital cameras. [Top]

Flash ROM: Memory that is non-volatile (data retained when the power is off) but may be erased and reloaded with data. Some manufacturers provide the operating system (OS) in flash ROM so that it is upgradable. [Top]

Form Factor: The most basic PDAs are credit-card sized, offering limited functionality and display readability along with low prices, long battery life and excellent portability. The classic PDA emphasized in this knowledge base is palm-sized (roughly 3" x 5" x 3/4"), lightweight (typically 4 to 8 ounces) and supports a variety of applications and accessories allowing user interaction through buttons, a stylus and optional accessory keyboard. Larger "handheld" devices often incorporate a full alphanumeric keyboard and larger display than the palm-sized PDAs. The next step up are the book-sized ultra-light notebooks weighing several pounds and offering a conventional desktop PC operating system. [Top]

Infrared Transceiver Port (IrDA): These ports use blinking infrared light beams, similar to TV remote controls, to exchange data between PDAs and PCs or other PDAs. This technology allows for synchronizing without using cables to connect the communicating devices. Also see Bluetooth. [Top]

Keyboard: Many PDAs accept add-on keyboard hardware, either tiny versions on which the user types with his or her thumbs or larger (often collapsable -- folding or roll-up) versions that support touch typing. The alternative is much slower text entry using a stylus. [Top]

Linux: A Unix-like operating system (OS) that is available at low or no cost because of its development as a publicly supported open-source project. PDA versions of the OS are now available. [Top]

Microprocessor: See CPU. [Top]

Modem: An interface device that permits serial communications using a telephone line or cell phone. PDA modems are either built in or installed using one of the expansion ports. Connections between a modem and cell phone might be supported by cable, infrared (IrDA) or Bluetooth. Also see wired modem and wireless modem. [Top]

Monochrome: See Color Depth. [Top]

MP3: See Personal - MP3 Music. [Top]

MS Office Integration: Some PDAs are able to exchange data with Microsoft's (or other's) desktop Office applications including word processing, spreadsheets and presentations. This capability may allow document review, preparation or revision activities to be performed with the PDA. Programs that support interaction with Microsoft Office products are included with the PocketPC operating system, and some similar capabilities are provided with various versions of the Palm OS or are available as third party software. [Top]

MS Office Integration - Word Processing: Because of their small screens and limited keyboarding capability, PDAs are not recommended for extensive word processing applications. Notes and memos are often prepared on these devices, and various keyboard options may be used to enhance the input process. Using synchronizing software provided with many PDAs (or separately acquired), it is possible to exchange word processing files between a desktop and PDA for remote reading and/or editing. [Top]

MS Office Integration - Excel Spreadsheet: Files representing Microsoft Excel spreadsheets may be downloaded to a PDA for review or modification using synchronizing software. [Top]

MS Office Integration - Powerpoint Presentations: Files representing Microsoft Powerpoint presentations may be downloaded to a PDA for review or modification using synchronizing software. The display resolution of PDAs is much lower than the resolutions in which presentations will normally be delivered, but a PDA could provide an effective method for reviewing presentations on the road. [Top]

Multi-tasking: See Pocket PC OS. [Top]

Operating System (OS): An OS provides support for applications that includes loading the software and supporting functions that most applications require including input and output such as communications and display. Entry level PDAs often use simple OSs that are proprietary to their manufacturer. Most mid- and upper-level PDAs use either the Palm OS or Pocket PC OS. Linux is also emerging as an option for PDA operating systems. [Top]

Palm Operating System: A proprietary operating system used in PDAs manufactured by Palm and also licensed to several manufacturers that produce Palm-compatible computers such as Visor's Handspring series and the Sony Clié. The Palm OS generally requires less RAM memory and CPU processing power than the Pocket PC OS and operates longer on a set of batteries or battery charge but supports less sophisticated computing capabilities and is not as compatible with the Microsoft Windows desktop OSs. Also see Operating System. [Top]

Passive-matrix display: The least expensive display technology for monochrome and color displays. Provides a lower image quality than an active-matrix display. [Top]

Personal: In addition to support for business or professional activities, most PDAs support (perhaps with add-on hardware/software) a variety of personal entertainment options. These include listening to music or audio books, reading electronic books, playing games and viewing (and sometimes taking) digital photos or video clips. [Top]

Personal - MP3 Music: Some PDAs support audio applications including MP3 playback. Integrated speakers and/or a headset jack will be required for this application, and additional software could be required. Music is downloaded to the PDA from a desktop/laptop computer to support the MP3 capability. [Top]

Personal - E-Books: The text of an electronic book (e-book) will be downloaded from a desktop/laptop computer and stored in the PDAs memory for later display. [Top]

Personal - Playing Games: A selection of PDA games is often included free with the initial software applications, and others are available as Internet downloaded shareware or freeware or as commercial software. [Top]

Personal - Digital Photos: To view digital photos (or short video clips) on a PDA, a high resolution color display (see colors) is recommended. By downloading digital images to a PDA, you can create a digital photo album to take with you on trips. Some PDAs accommodate a digital camera accessory or provide a built-in camera. [Top]

PIM (Personal Information Management): PIM software automates many of the record keeping tasks historically accomplished with printed planning notebooks. Example tasks include maintaining contact information and managing calendars for meetings and other appointments. PIM software for the PDA is often included in the purchase price along with desktop software with which it synchronizes. Some of these PDA PIM applications also synchronize with desktop/notebook PIM software from independent vendors, permitting easy use of the PDA with software that may have been adopted as a corporate standard. [Top]

PIM Calendaring: This is the appointment book and scheduling application. The PDA may be able to sound an alarm to warn you of an impending appointment. [Top]

PIM Contact Management: This application keeps track of addresses and phone numbers. [Top]

PIM To-Do Lists: An application that keeps track of (and helps manage) tasks that need to be accomplished. [Top]

Pocket PC Operating System: Replaced Microsoft's Windows CE for PDA use early in 2000. This is a multi-tasking operating system (can run more than one application at a time, memory permitting) and comes with a variety of applications that interface with desktop Windows applications. Also see Operating System. (Note: Pocket PC is often abbreviated "PPC"). [Top]

Professional/Travel: Because of their small size and light weight, PDAs are often used to support business or other professional activities that need to be performed anytime/anyplace. Many of these activities will have a travel-related aspect, such as navigating to meeting locations, finding hotels and restaurants or managing financial affairs on the road. [Top]

Professional/Travel - Digital Recording: Many PDAs support audio applications including digital voice recording and playback. An integrated microphone, speakers and/or headset jack will be required this applications, and additional software (perhaps available as shareware or freeware) might be required. [Top]

Professional/Travel - Financial/Portfolio Management: Checking the status of investments, performing trades on-line or interacting with bank accounts are all examples of financial management activities that may be performed through a PDA from remote locations. These are specific examples of applications supported by wireless e-mail and/or wireless Web access. There are also applications that facilitate exchanging data with desktop money management programs (e.g. Microsoft Money). [Top]

Professional/Travel - Navigation: With the right software and add-on hardware, a PDA can help you navigate unfamilar city streets by displaying maps. Information on restaurants, hotels and other support or entertainment facilities is sometimes available with these applications. To provide more sophisticated navigation support, some PDAs may be equipped with a GPS (Global Positioning System) receiver that identifies the location of the PDA. When integrated with map data, this allows the PDA to provide walking or driving directions. [Top]

Random Access Memory (RAM): The amount of volatile (erasable) memory used to store data and applications is stated in megabytes (MB) (millions of bytes or characters). Extra memory may allow use of a wider variety of applications, allow more applications to be in use simultaneously or let applications run faster. PDAs are often sold with varying amounts of built-in RAM: 8 megabytes or more is typical for PDAs using the Palm OS and 32 megabytes or more is typical for Pocket PC-based devices. With some models, RAM may be expanded with plug-in cards used with expansion slots. Because PDAs do not have disk drives, all applications and data must be loaded into RAM and/or ROM. [Top]

Reflective display: In this display mode the screen is illuminated entirely by reflected light, minimizing power consumption but making the display difficult to use in low light conditions. Also see Backlit Display. [Top]

Read Only Memory (ROM): Memory that is not erased when the power is shut off or changed by program actions. Used to store the operating system and applications software. Some PDAs use "flash" ROM that permits upgrading the operating system as new versions are developed. [Top]

Shareware and Freeware: Two sources of low-cost software for PDAs. Shareware is software that you typically acquire as an Internet download and try, then pay for if you decide to keep using it. Shareware costs are usually nominal and becoming a registered user might provide extras such as an enhanced version or printed documentation. Freeware is software that is completely free of charge. Examples of shareware and freeware for the Pocket PC can be found in the "Downloads" section of PocketPC Magazine's Web site. [Top]

Stylus: Palm-sized PDAs without keyboards accept text input in several ways. A "soft" keyboard displayed on the screen allows text input by tapping the letters with a pencil/pen shaped stylus. Handwriting recognition software (Graffiti for the Palm OS, Transcriber for the Pocket PC OS) allow input of (carefully!) printed letters using the stylus. Also see Keyboard. [Top]

Synchronizing PDAs with PCs: Moving information between a PDA and desktop or notebook PC requires software on both devices as well as an electronic connection. Examples include direct cable connections (serial or USB), cable connections with a docking station (serial or USB) that holds the PDA, infrared transceiver ports and wireless networking including wireless LANs and Bluetooth. Information to be synchronized is stored on both the PDA and desktop computers and each record is date/time stamped. When the PDA and desktop are synced, the latest record is retained on both devices. The PDA buyer must be sure that synchronizing software that works with the desired PDA is available for the desktop operating system and desktop applications that they intend to use. PDAs based on the Palm OS generally come with software supporting synchronization with with both Apple Macintosh computers and those running Microsoft's operating systems. Pocket PCs require third party software to synch with the Macintosh. Synchronizing Palm OS or Pocket PC OS PDAs with Lotus Notes usually requires additional software. [Top]

TFT (Thin Film Transistor): See Active-Matrix Display. [Top]

USB: Universal Serial Bus (USB) is a high speed serial connection available on most recent models of desktop and notebook PCs and on many PDAs. USB equipped devices are connected with a USB cable. [Top]

Web Clipping: Web sites are typically formatted for much higher screen resolutions than PDAs offer, and are usually delivered over higher-speed connections than are available for PDAs used through a wireless network. To deliver essential content while avoiding the problems caused by these two issues, some wireless services provide Web data from selected Web sites reformatted to contain only essential text information. Examples include news, travel and financial sites. [Top]

Wi-Fi (IEEE 802.11b standard): (Wireless Fidelity) See Wireless LAN. [Top]

Wired Modem: A modem that provides network access through a cabled connection to a conventional telephone or cell phone. [Top]

Wireless Modem: A modem that provides self-contained wireless access to the Internet or another network: no telephone or cell-phone is required. [Top]

Wireless Local Area Network (LAN): A network based on radio frequency communications to exchange data instead of cabled connections. Access to wireless networks is becoming increasingly available in public spaces such as airports. Subscribing to a wireless networking service is usually required for such access. Also see wireless modem and Wi-Fi. Some PDAs allow the use of Bluetooth wireless connectivity to connect to a Bluetooth-enabled cell phone, providing another approach to wireless connectivity. [Top]