How PDAs Work


Essential Gadgets Image Gallery A typical PDA: the Hewlett Packard iPAQ Pocket PC. See more pictures of essential gadgets.

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 a look at the PDA -- where it's been, how it is converging with other devices, and where it's headed. We'll also examine how PDAs work and give you some pointers on how to select one.

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The Birth of the PDA

Predecessors of the modern PDA include the Psion Organiser and the Sharp Wizard. These early devices, which were intended to be portable computers, came out in the mid- to late 1980s. They included small keyboards for input, a small display, and basic features such as an alarm clock, calendar, telephone pad and calculator. Support for specialized software such as games and spreadsheets was also included. The Psion Organiser II, released in 1986, was especially popular and more than half a million were sold.

In 1993, Apple introduced the Newton MessagePad at a price of $700. It provided users with an electronic notepad, to-do list, calendar, telephone log and address file applications. Some of the Newton's innovations have become standard PDA features, including a pressure-sensitive display with stylus, handwriting recognition capabilities, an infrared port and an expansion slot. However, the Newton MessagePad was too big, expensive and complicated, and its handwriting recognition program was poor. Apple discontinued the Newton in 1998.

The original PalmPilot was introduced in March of 1996 by Palm Computing (owned by U.S. Robotics at the time). It cost less than $300, ran on its own Palm operating system, fit in a shirt pocket and synchronized with consumers' PCs. The PalmPilot ran for weeks on AAA batteries, was easy to use, and could store thousands of contacts, appointments and notes. Part of its small size was due to the lack of a keyboard. Users used a stylus and the Graffiti language to input data.

Not to be outdone, Microsoft had been working on various forms of portable computing, including PenWindows and tablet computers. In November 1996, Microsoft released Windows CE, its first operating system for mobile devices. A number of manufacturers, such as HP, Compaq and Casio, adopted it for what was dubbed the Handheld PC -- the first Windows-based competitor for the PalmPilot.

In the next section, we'll look at the types of PDAs on the market today.

Types of PDAs

palmOne Tungsten T5 Handheld
palmOne Tungsten T5 Handheld
Photo courtesy HowStuffWorks Shopper

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.

Palm PDAs

Most Palm devices are made by palmOne, which offers the Zire and Tungsten product lines. The company formed in 2003 when Palm Computing acquired Handspring, Inc. Sony, which produced the Palm-based CLIE, stopped producing PDAs in 2005.

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.)

Pocket PCs

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

Smartphones

palmOne Treo 650 Handheld
Photo courtesy HowStuffWorks Shopper

A smartphone 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.

In the next section, we'll look at what PDAs do and how they do it.

PDA Features

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.

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 PDA Functions

SanDisk 256 MB Secure Digital Card
SanDisk 256 MB Secure Digital Card
Photo courtesy HowStuffWorks Shopper

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's 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

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
  • Built-in GPS capabilities
  • 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 

In the next section, we'll look at the computer that powers a PDA.

The PDA Computer

The parts that can make up a PDA
The parts that can make up a PDA

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 functions according to programmed instructions. Unlike desktop PCs and laptops, PDAs use smaller, cheaper microprocessors. Although these microprocessors tend to be slower than their PC counterparts, they're 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 disk. 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.

Here's an inside view of a PDA. The circuit board folds away from the screen. In the middle of the single-layer circuit board is the microprocessor, and to the left and above are the memory chips.

PDAs and smartphones 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 smartphones.

In the next section, we'll look at the other parts that make up a PDA.

PDA Battery

Here are the parts of the PDA -- the case, the LCD screen and the circuit board. This model comes in basic black, but you can buy interchangeable covers in various colors.
Here are the parts of the PDA -- the case, the LCD screen and the circuit board. This model comes in basic black, but you can buy interchangeable covers in various colors.

So far, we've looked at the PDA's microprocessor, memory and operating system. Now let's look at the other parts of a PDA.

Batteries

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 currents. 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 Bluetooth or a USB port. Each model also has a few buttons and navigation dials to bring up applications and scroll through files.

 

PDA Display and Input

This BlackBerry has a large LCD display screen.
This BlackBerry has a large LCD display screen.
©2007 HowStuffWorks

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 Bluetooth or a USB port. Each model also has a few buttons and navigation dials to bring up applications and scroll through files.

Buying a PDA

If you're in the market for a PDA, the main question you should consider is, "What will I be using this for most of the time?" If you're looking for basic PIM functions and organization, you probably don't need wireless connectivity. On the other hand, if you travel frequently and want to stay in touch via e-mail, you need Wi-Fi capability or a smartphone with cellular data service.

Because most people use a PDA as a PC accessory, synchronization is an important consideration. Look for a device that easily synchronizes with the PIM software you use on your computer. For example, if you have a Macintosh computer or you don't use Microsoft Outlook, a Palm OS device may be more to your liking.

The device's data entry method is another important consideration. If you plan to use your PDA for e-mail or other text-heavy applications, consider a built-in keyboard. If you can, try out the keyboard before you buy.

The size and shape of the device and its display are also important considerations. The device should be comfortable to hold. The display size and clarity should also meet your expectations. As with the keyboard, it's best to make a trip to a store that sells the devices you're interested in so you can try it out before you buy.

If you are interested in a multipurpose device that combines features such as GPS, an MP3 player, or digital camera, look for a device that has these features integrated. Alternatively, you can opt for a device with an SDIO slot and use compatible SDIO peripherals. If you plan to use numerous applications or store large files, look for a device that accepts flash memory media cards.

Accessories to consider include an additional battery, a car or travel charger, headphones, a carrying case, a plastic screen protector and add-on keyboards.

If you're interested in a smartphone, many of the considerations for purchasing a cell phone apply. Some of the most important things to check include service providers' coverage area, the additional cost for cellular data service (if any), and the length of the service contract. For more information, see How Buying a Cell Phone Works. You should also consider the capabilities of the different smartphone operating systems, such as Symbian, BlackBerry , Palm OS and Windows Mobile Pocket PC Phone edition.

The Future of PDAs

Traditional PDAs appear to be less popular than they have been in the past. Several manufacturers have exited the PDA market, including Sony and Toshiba. Sales of traditional PDAs have declined in recent years, according to IDC's Worldwide Handheld QView press release dated February 2, 2005.

For the future, PDAs need to continue to add to their core PIM functions in order to survive. The emergence and gaining popularity of smart phones and devices that combine other features such as wireless Internet, GPS and multimedia capabilities seem to back this trend.

For answers to frequently asked questions about PDAs, check out the FAQ on the following page.

PDA FAQ

These Smartphones range in price depending on their features.
These Smartphones range in price depending on their features.
©2007 HowStuffWorks

Here are answers to some frequently asked questions about PDAs.

Why would I need a PDA?

A PDA might be helpful if you:

  • Have a lot of addresses and phone numbers that you need to have with you all the time
  • Have a lot of dates and appointments to keep track of, both personal and business, and need to see at a glance whether you have a conflict when you're trying to set up appointments
  • Have more than one calendar to keep up with
  • Are the busy or forgetful type, and could use automatic reminders of appointments
  • Spend a lot of time away from your desktop or laptop, but still need the information that's stored there
  • Need to check e-mail or access the Internet frequently, even when you're traveling or just away from your computer
  • Can't afford a laptop but need some e-mail or word processing capability away from your desktop
  • Are willing to spend the time to learn how to use your PDA and transfer data to it

How much do PDAs cost?

PDAs range in cost from about $150 to $1,000, depending on the features you decide to buy. Most are in the range of $300 to $500.

Can my PDA work with my desktop or laptop?

PDAs are designed to work with desktops or laptops and to make the information in your bigger computers portable. So you need to keep the information up-to-date. PDAs have features that make this easier for you. The communication between PDA and PC is referred to as data synchronization or syncing. This is typically done through a serial or USB port on the PDA. Some PDAs have a cradle that they sit in while hooked up to the PC. Many PDAs also have an infrared communications port that uses infrared (IR) light to beam information to a PC or another PDA. Some PDAs also offer wireless methods to transfer data to and from a PC/PC network through a wireless e-mail /Internet service provider like those available on new models of cell phones. Finally, some PDAs offer telephone modem accessories to transfer files to and from a PC/PC network.

Which operating system is best for PDAs?

Each operating system has its advantages. The Palm OS is the market leader, so there is a lot of software written and being developed for it. But developers are working on software for the PocketPC systems, too. Palm OS takes up less memory and runs faster, and users say it is easier to use. PocketPC easily supports color displays, graphics, standard Windows packages (Word, Excel), and other devices (such as built-in MP3 players or MPEG movie players). PocketPC takes up more memory and is slower, and users say it is more complicated.

Other Common PDA Questions

Wireless internet can be accessed through most PDAs.
Wireless internet can be accessed through most PDAs.
©2007 HowStuffWorks

If my PDA is stolen, which seems possible since they are so small, is there anything I can do to protect my personal data?

If you keep your PDA data synchronized with your desktop computer, you'll always have a back-up copy. So if you lose your PDA, you'll still have the data. You can also do several things to lock up your PDA's information. In most models, you can use password protection. There are security programs available, too, that can keep someone from getting to your data. And some applications provide encryption.

How does a PDA work with the Internet?

One thing that PDA makers have done to make their devices work better for Internet access is a process called Web Clipping. Instead of downloading whole Web pages, Web Clipping slices out bits of text information and sends it through the airwaves to your PDA. News headlines, phone numbers, e-mail and other information can be transmitted this way.

Can handheld computers get viruses?

Viruses have infected some PDA models. The Phage virus, for example, overwrites some of Palm's executable files. Several companies have devised anti-virus software for PDAs. If you download programs from the Internet, you can be vulnerable to viruses. You have to watch out for the same things that you would if you downloaded a file to your desktop computer. Be cautious about downloading a file or program that comes from a source you don't know. To find out more about computer viruses, read How Computer Viruses Work.

How quickly will a PDA run out of memory?

The data commonly stored on PDAs doesn't take up much memory -- it's mostly text without images, so you can store a lot before you run out of room. Some PDAs need more memory for their operating systems; and if you use your PDA for e-mail or accessing the Internet, you'll need more memory. If you worry about having enough, you could choose a model that has expandable memory.

If I buy a PDA today, how soon will it be outdated?

PDA development, like the rest of the computing world, moves very quickly. The models available today have more functions and can be less expensive than the models available a few years ago. Eventually, PDAs will merge with cell phones and use a cellular network to communicate via voice as well as text. It is also likely that PDAs will become faster and have more memory as computer technology advances. The key to buying a PDA that suits you is to consider what you will use it for, then buy the model that will fill that need. Think of the function rather than the form. For example, if your primary need is for an organizer to keep your appointments and contacts, you will be able to use any good PDA for years to come. If you are the kind of person who develops "computer envy," then you might look for an upgradeable model and watch for the latest software.

On the next page, you'll find out about PDA software programs that'll make your job simpler and easier.

PDA Software

PDA software programs let professionals
PDA software programs let professionals
© Photographer: Elena Elisseesa | Agency: Dreamstime

Most PDAs come with a sync program that synchronizes and updates information on both your computer and your PDA. Microsoft Pocket PCs use software called ActiveSync; Palm OS products use HotSync; and BlackBerry has Desktop Software.

For all PDAs, the process of downloading and installing new software is more or less the same:

  1. Download the software file onto your computer's desktop.
  2. Connect your PDA to your computer, either through a cradle or directly into a USB port.
  3. Run your sync software: press a button on your PDA, a button on the cradle, or open the sync program on your computer.
  4. On your desktop, double click on the downloaded file you want to install on your PDA.
  5. The software will open an installation wizard that'll walk you through the process.

PDAs have always been an essential tool for the busy executive. Today's PDA software allows professionals to say organized as well as connected. They can work no matter where they are.

Most PDAs come standard with an office application suite (word processor, spreadsheet, etc.), a Web browser and an e-mail program. Traveling executives can open e-mail attachments with their PDA, edit documents and send them back to associates while on the road.

Now that most PDAs have Internet connectivity, PDA software applications allow access to real-time online data.

Some of the professionals using PDA software applications are:

  • Travelers
  • Shipping managers
  • Salesmen and real estate agents
  • Doctors and nurses
  • Lawyers
  • Police officers databases

[Sources: Handango, Sage Software, CollectiveMed and Orbitron Technologies]

But PDAs aren't used just for business. The same software can be used to download and play games like chess, Sudoku and backgammon.

There's also PDA software that allows you to record DVDs for playback on your handheld device, and other programs that turn your PDA into a portable photo album, MP3 player or eBook reader.

So, if you use your PDA for business or pleasure, just remember that there's software working behind the scenes to make it all possible.

For more information about PDA software and related topics, check out the links on the next page.

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