The main purpose of a personal digital assistant (PDA) is to act as an electronic organizer or day planner that is portable, easy to use and capable of sharing information with your PC. It's supposed to be an extension of the PC, not a replacement.

PDAs, also called handhelds or palmtops, have definitely evolved over the years. Not only can they manage your personal information, such as contacts, appointments, and to-do lists, today's devices can also connect to the Internet, act as global positioning system (GPS) devices, and run multimedia software. What's more, manufacturers have combined PDAs with cell phones, multimedia players and other electronic gadgetry.



As its capabilities continue to grow, the standard PDA device is changing. In this article, we take look at the PDA -- where it's been, how it is converging with other devices, and where it's headed. We also examine how PDAs work and give you some pointers on how to select one.

Types of PDAs

1 Traditional PDAs

Today's traditional PDAs are descendents of the original PalmPilot and Microsoft Handheld PC devices. Palm devices run the Palm OS (operating system), and Microsoft Pocket PCs run Windows Mobile. The differences between the two systems are fewer than in the past.




Known for their ease of use, Palm OS PDAs have:

> A vast library of third-party applications (more than 20,000) that you can add to the system (most devices come bundled with e-mail, productivity, and multimedia software)

> An updated version of the Graffiti handwriting-recognition application

> Synchronization with both Windows and Macintosh computers using the Palm Desktop

> Smaller displays than Pocket PCs to accommodate a dedicated Graffiti area on the device (Some higher-end Palm devices now incorporate a virtual Graffiti area in the display, resulting in a larger display area.)

most of the pdas are made by palmone.The company formed in 2003 when Palm Computing acquired Handspring, Inc. Sony, which produced the Palm-based CLIE, stopped producing PDAs in 2005.

Pocket PC is the generic name for Windows Mobile PDAs. Their standard features include:

> Pocket versions of Microsoft applications such as Microsoft Word, Excel, and Outlook (note that some formatting is lost between Pocket and standard versions of documents)

> Synchronization with Microsoft Outlook on a Windows PC (synchronization with e-mail systems other than Outlook or with Macintosh computers requires additional software)

> Three handwriting-recognition applications: Transcriber, Letter Recognizer (similar to the new version of Graffiti), and Block Recognizer (similar to the original Graffiti)

> A virtual writing area, which maximizes the display size
Windows Media Player for multimedia content

Smart Phones

A smart phone is either a cell phone with PDA capabilities or a traditional PDA with added cell phone capabilities, depending on the form factor (style) and manufacturer. Characteristics of these devices include:

> A cellular service provider to handle phone service (As with cell phones, you typically purchase a cellular plan and smart phone from the service provider.)

> Internet access through cellular data networks

> Various combinations of cell phone and PDA features, depending on the device (for example, not all smart phones offer handwriting-recognition capabilities)

> A number of different operating systems, including Windows Mobile Pocket PC Phone Edition, the Palm OS, the Blackberry OS for Blackberry smart phones, and the Symbian OS for smart phones from Panasonic, Nokia, Samsung and others



Well, it doesn't look like a PDA...

Related devices include ultraportable computers, smart watches and multimedia players. Ultraportable computers range in weight from less than a pound to about three pounds, come with a full desktop operating system (such as Windows XP), and include a small keyboard. Smart watches offer some PDA functions in a wristwatch form factor. Microsoft's SPOT (Smart Personal Objects Technology)-based watches, for example, can receive MSN Direct information such as weather and news. They can also receive calendar information and personal messages. Some multimedia players can combine the functions of a PDA with multimedia features such as a digital camera, an MP3 player and a video player. For example, the Tapwave Zodiac comes with an SDIO slot that accepts a Wi-Fi card for e-mail and Web support.

What PDAs Do

The Basics

Even the most basic PDAs handle standard personal information management (PIM) functions, run application software and synchronize with PCs. Here are some additional details about these basic features.
Handle Standard PIM Functions
All PDAs come with some kind of personal information management (PIM) software that typically handles the following tasks to keep you organized:

Store contact information (names, addresses, phone numbers, e-mail addresses)
Make to-do lists
Take notes
Track appointments (date book, calendar)
Remind you of appointments (clock, alarm functions)
Perform calculations

Run Application Software
PDAs can run specialized software applications:

Windows Mobile devices come with Pocket versions of Word, Excel, Internet Explorer, and Outlook (includes e-mail and PIM functions), along with Windows Media Player and voice memo recording.

Most Palm OS devices include applications such as DataViz Documents to Go (compatible with Microsoft Word, Excel, and PowerPoint), palmOne Media (for photos and video), VersaMail e-mail software, and web-browsing software.

All types of devices can run other kinds of software including games, multimedia, expense, diet and exercise, travel, medical, time and billing and reference. You can obtain PDA software online from a number of sources including Handango (all devices), PocketGear (Windows Mobile/Pocket PC devices), and palmOne Software Connection (Palm OS devices).

Synchronize With PCs
Because PDAs are designed to complement your PC, they need to work with the same information in both places. If you make an appointment on your desktop computer, you need to transfer it to your PDA; if you jot down a phone number on your PDA, you should upload it later to your PC.

Synchronization software on the PDA works with companion software that you install on your PC. Microsoft Pocket PC devices use ActiveSync and Palm OS devices use HotSync synchronization software. On your computer, you also need an application like Microsoft Outlook or the Palm Desktop that holds PIM information on the PC side.

The beauty of synchronization is that you always have a backup copy of your data, which can be a lifesaver if your PDA is broken, stolen, or completely out of power.

Common Functions
Today, most PDAs incorporate wireless and multimedia functions of some type. Functions found on most (but not necessarily all) devices include:

Short-range wireless connectivity using Infrared (IR) or Bluetooth technology IR is found on most PDAs and requires a clear line of sight. It is commonly used to sync with a notebook computer that has an IR port. Bluetooth wirelessly connects (it's a radio frequency technology that doesn't require a clear line of sight) to other Bluetooth-enabled devices, such as a headset or a printer.

Internet and corporate network connectivity through Wi-Fi and wireless access points

Support for Wireless WAN (Wide Area Networks); the cellular data networks that provide Internet connectivity for smart phone devices

A memory card slot that accepts flash media such as CompactFlash, MultiMediaCard, and Secure Digital cards (Media cards act as additional storage for files and applications.)

Audio support for MP3 files and a microphone, speaker jack and headphone jack



Bells & Whistles
High-end PDAs offer multimedia, security and add-on features not found on less expensive devices:

A Secure Digital Input/Output (SDIO) card slot for add-on peripherals contained in an SDIO card, for example, a Bluetooth card, a Wi-Fi card, or a GPS (global positioning system) card

A built-in digital camera for snapping digital images and capturing short videos (The quality will not be as good as that of a dedicated camera.)

Integrated security features such as a biometric fingerprint reader.

Built-in GPS capabilities

PDA Parts

Microprocessors and Memory
Like standard desktop and laptop computers, PDAs are powered by microprocessors. The microprocessor is the brain of the PDA, and it coordinates all of the PDA's functions according to programmed instructions. Unlike desktop and laptop PCs, PDAs use smaller, cheaper microprocessors. Although these microprocessors tend to be slower than their PC counterparts, they are adequate for the tasks that PDAs perform. The benefits of small size and price outweigh the cost of slow speeds.



A PDA doesn't have a hard drive. It stores basic programs (address book, calendar, memo pad and operating system) in a read-only memory (ROM) chip, which remains intact even when the machine shuts down. Your data and any programs you add later are stored in the device's random-access memory (RAM). Information in RAM is only available when the device is on. Due to their design, PDAs keep data in RAM safe because they continue to draw a small amount of power from the batteries even when you turn the device off.

Less powerful PDAs have lower amounts of RAM. However, many application programs take up significant memory space, so most models have more memory. Also, Pocket PC devices generally require more resources and have even more RAM. To provide additional memory, many PDAs accept removable flash media add-on cards. These are handy for storing large files or multimedia content, such as digital photos.

Some newer PDAs, such as the Palm Tungsten E2, use flash memory instead of RAM. Flash memory is non-volatile, which means it preserves the data and applications it stores--even when all battery power is depleted.

Operating Systems

The operating system contains the pre-programmed instructions that tell the microprocessor what to do. The operating systems used by PDAs are not as complex as those used by PCs. They have fewer instructions, which require less memory.

PDAs and smart phones typically have one of two types of operating systems: Palm OS or Windows Mobile. However, RIM makes a specific OS for its Blackberry devices, and the Symbian OS operates some smart phones

More Parts

PDAs are powered by batteries. Some models use alkaline (AAA) batteries, while others use rechargeable batteries (lithium, nickel-cadmium or nickel-metal hydride). The battery life depends on what kind of PDA you have and how you use it. Here are some of the things that can drain batteries:
Operating system (PocketPC requires more power by virtue of its increased memory requirements)
More memory
Wireless connections, such as Wi-Fi and Bluetooth
Backlighting on the display
Battery life can vary from hours to months, depending upon the PDA model and its features. Most PDAs have power management systems in place to extend the battery life. Even if the batteries are so low that you can no longer turn the machine on (it will give you plenty of warning before this happens), there's usually enough power to keep the RAM refreshed.
If the batteries do run completely out of juice or if you remove them, most devices have an internal backup battery that provides short-term power (typically 30 minutes or less) until you install a replacement. If all power sources are depleted, PDAs lose all of the data in RAM. This makes backing up or synchronizing your PDA extremely important.

In addition to battery power, many PDAs come with AC adapters to run off household electric current. A car adapter is also generally available as an accessory.



LCD Display
PDAs use an LCD (liquid-crystal display) screen. Unlike the LCD screens for desktop or laptop computers, which are used solely as output devices, PDAs use their screens for output and input. The LCD screens of PDAs are smaller than laptop screens, but vary in size. Almost all PDAs now offer color displays.

PDA displays have the following features:

Transflective TFT (thin-film transistor) LCD for indoor and outdoor use
Different pixel resolutions with higher resolutions for better quality
Color screen
Backlighting for reading in low light
Input Methods
PDAs vary in how you input data and commands. Some devices use a stylus and touch screen exclusively in combination with a handwriting recognition program. Using a plastic stylus, you draw characters on the device's display or dedicated writing area. Software inside the PDA converts the characters to letters and numbers. On Palm devices, the software that recognizes these letters is called Graffiti. Graffiti requires that each letter be recorded in a certain way, and you must use a specialized alphabet. For example, to write the letter "A," you draw an upside-down V. The letter "F" looks like an inverted L. To help Graffiti make more accurate guesses, you must draw letters on one part of the screen and numbers in another part.

Pocket PC PDAs offer three handwriting-recognition applications: Transcriber, Letter Recognizer and Block Recognizer. Letter Recognizer and Block Recognizer are similar to Graffiti and require specialized alphabets. By contrast, Transcriber recognizes your "regular" handwriting, as long as you write legibly. It is similar to the handwriting recognition capabilities found on Tablet PCs.



If you can't get the hang of PDA handwriting, you can use a miniature onscreen keyboard. It looks just like a regular keyboard, except you tap on the letters with the stylus. In addition, many devices now include a small (and usually cramped) QWERTY keyboard. Some of these require you to use your thumbs to type. And you can use a full-size keyboard by connecting it to the PDA via a Bluetooth or USB port. Each model also has a few buttons and navigation dials to bring up applications and scroll through files.
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SD
Hardwaredude.com Team