PDAs Buying Guide

Buyers' Guide to PDAs Contents

• Operating system
• Microsoft
• Palm
• Symbian
• RIM
• Tech specs
• Memory
• Form factors
• Screen
• Size
• Touchscreen vs Keypad
• Battery
• Connectivity
• Bluetooth
• WiFi
• GSM/GPRS
• GPS
• Multimedia

Personal digital assistants (PDAs) are data-centric devices designed for on-the-move computing and communications. PDAS are a complete contact database with storage for phone, address and email details, calendar and appointment scheduling, memos and to do lists. They are also mobile computing devices for office functions such as reading and editing word documents, spread sheets, PDFs and other files. In addition to data applications, some models are appearing that include phone functionality, such as voice-activated phone dialing, messaging and global roaming.

PDAs come in a range of shapes and sizes from low-end models that can be used in place of a paper diary to high-end models that are intended for global mobile computing and connectivity with a suite of business applications. There's almost a model for every application and, if manufacturers have their way, we'll all by discarding our humble diaries in place of these digital devices.

Operating system

When choosing a PDA, you're also choosing an operating system and this will affect functionality, applications and third-party software. It's important to get the most suitable platform for your intended tasks. You'll have to choose between Microsoft, Palm, Symbian and RIM.

Microsoft

The Microsoft Windows Mobile operating system appears on a number of PDAs from manufacturers including O2, i-mate, Dell, Acer and HP. It has the dominant share of the PDA market and there are a number of versions within the Windows Mobile family that update earlier versions with enhancements and additional features.

Windows Mobile 2003 for Pocket PC Second Edition included improvements such as support for increased screen resolution and dual screen orientation for viewing in both portrait and landscape modes. The Windows Mobile 2003 Pocket PC Professional Edition and Premium Edition included Media Player 9, Pictures, a photo editing application, and improvements for connections between device and network. The Premium Edition also included Microsoft Reader.

The latest version is Windows Mobile 5.0, which is used in PDAs with voice and phone functionality, and smartphones. It supports a range of devices with different screen sizes, and an increased number of files for synchronisation with Outlook. It also has the addition of PowerPoint viewer, improved Media Player and support for wireless network connections through WiFi and Bluetooth.

Palm

The other major player in the PDA market is Palm which has a number of low- and high-end PDAs. The most recent version of the operating system is Palm OS 5.4, also known as Garnet, an improved version of the older OS 5.0 which is still in models in the marketplace. The additions include support for higher resolution screens, more memory and improvements with Bluetooth connectivity. Palm has a large group of third-party applications and add-ons for business and personal tools, such as flight scheduling, money management and shopping lists.

Symbian

The Symbian operating system is more commonly found in smartphones, but some of these devices have computing functionality and can sit in both the smartphone and PDA categories. Devices based on the Symbian operating system tend to favour phone features, but the data applications are improving with each new version of the operating system. The latest version of the operating system is Symbian OS v9 which has improved security, enhanced email and calendar functions, support for higher resolution cameras and better video and image processing.

RIM

The newest entrant to the growing PDA market is RIM (Research in Motion) with its BlackBerry devices. It is a proprietary platform that was originally developed for sending and receiving email. BlackBerry devices now support Microsoft Exchange, Lotus Domino, Novell Groupwise and POP3/IMAP email clients. The platform has also developed to include a range of information management tools as well as phone functions in some models. Palm has recently announced that BlackBerry connect will be available on the Treo smartphone in 2006. However, most BlackBerry devices have limited office applications, storage and multimedia features.

Tech specs

Processing power varies across the range of PDAs according to price and functionality. As with most computing devices, newer models make improvements with processing power and speed.

PDAs with an Intel XScale PXA27x processor tend to be found in devices at the high end of the market geared toward speed and maximum processing power. Speeds range between 104MHz and 624MHZ. The PXA270 processor included enhancements for audio and video performance and 3D graphics as well as other CPU improvements.

The Intel PXA26x processor group is based on 32-bit processor in 200MHz, 300MHz and 400MHz versions which allow more capabilities into the device by stocking chips and reducing the number of components. The PXA255 runs at 200MHz, 300MHz and 400MHz and offers reduced power consumption compared to older processors.

PDAs running a Samsung S3C2410 or S3C2440 processor, which are based on an ARM920T core, can run at 230MHz and 266MHz. This processor is more often used in cheaper devices because of the system-on-a-chip design that integrates some features within the chip itself. The chip is available with flash memory, SD RAM and support for SD and MMC card slots. It can be used with Windows, Palm and Symbian devices. The Texas Instruments OMAP processors are used in some PDAs and are most often found in devices that include phone functionality. There are a number of versions, including OMAP3xx, 1510, 161x, 1710 and 2420, with the 310 and 1570 common in business-oriented devices.

Memory

Most PDAs feature two types of memory - RAM and ROM. RAM is used by the processor to hold data that is accessed while the computer is running, and the data is loaded and reloaded as the device is turned on and off. The more RAM, the faster the processor can work because it accesses more information from memory rather than the hard drive. ROM, or Read Only Memory, is also sometimes referred to as non-volatile memory because it is not lost or reloaded when the device is turned on or off.

In devices where memory is used by applications, it can reduce the amount of storage space available for user data. The range for RAM is between 16MB and 256MB, although BlackBerry devices tend to be somewhat lower. Some advertisements will state the separate figures for RAM and ROM, which gives a better idea of actual user storage capacity. Others may just list the RAM or Memory figure, which also includes the storage capacity for user data.

Some devices are appearing on the market that have hard drive storage. The Life Drive, for example, has a 4GB hard drive and 3.85GB is available for user storage. Most PDAs also include a slot for a removable memory card that is used for storing data between transfers and updates with the PC, or for some applications or files. They range in capacity from 128MB to 2GB depending on the format. Most PDAs will have a multi-format slot that can take one or more cards in formats such as SD, miniSD, MMC, CF (I and II) and SDIO. For more on removable memory cards, see the buying guide on storage cards.

Form factors

Screen

Screen size, resolution and colours have been steadily improving in PDAs over the years. Expect 4000 colours and a screen resolution of 160x160 pixels in low-end models, with 65K and 320x480 pixels in the more expensive models that feature larger screens. Some models allows the screen to be used in either portrait or landscape, but this depends on the size and type of device and whether the operating system supports this functionality. It's a useful feature for web browsing and reading documents. Transflective screens are backlit for indoor use can absorb the sun's ray when outdoors, to ensure a readable screen in bright light. A TFT (thin film transistor) screen gives better resolution and brightness because each pixel is lit individually.

Size

The PDA market has diversified and there are a range of models to suit different needs, applications and budgets. Accordingly, form factors vary depending on the applications and power on board. Low-end models, designed to replicate a diary, tend to be lighter and smaller, but have smaller screens, less processing power and fewer applications. Models with large screens tend to be bigger and heavier, but have processing power and storage capacity for weeks out of the office.

Touchscreen vs Keypad

Some models use a touchscreen, while others have a keypad. Some devices also have one or two programmable buttons for quick access to regular tasks or commonly used applications. Models with a touchscreen need a stylus to activate the applications and input data. Some PDAs have handwriting recognition software, such as Palm Graffiti or Block Recognizer and Letter Recognizer for Windows devices, which requires learning some pre-set characters for data input. Transcriber, which runs on Windows devices, will attempt to read a user's own handwriting and convert it to text.

A device with both touchscreen and keypad offers the best functionality; however, it may come at the expense of reducing screen size and keypad size. Small keypads tends to be multi-press alphanumeric to save space, while larger devices have the space for a Qwerty-style keypad. A standalone keyboard, which plugs in or is wireless, is an option to speed up data entry in devices with only a touchscreen or small keypad.

Battery

The most common types of battery are Li-Ion (Lithium-Ion) and Li-Ion Polymer, a lighter variant used in compact devices because it can be shaped to fit the device. Battery life depends on many factors, such as type of battery and processor, as well as battery saving features like screen shut down. In general, a 1300mAh Li-Ion battery will give about four to 10 hours of talk time, and 200 to 300 hours standby time.

Connectivity

USB connectivity is standard across PDAs and provides fast, efficient data transfer and recharging. Dock connectors are less common for synchronisation, but are included with some models. Any of the Microsoft Windows OS devices will easily synchronise with Outlook for email, contacts, memos and to do lists. Palm OS devices will support Outlook for synchronisation, as well as its own Palm Desktop application.

Synchronisation is also used to transfer files, such as multimedia files, applications and other data, between PDA and desktop computer. PDAs with infra-red connectivity can transfer data between a PDA and desktop PC or another device by beaming data such as virtual business cards and contact details at a speed of 115.2Kbps.

Bluetooth

Bluetooth is a wireless technology for data transmission at up to 3Mbps, which is also used in smartphones and 3G phones. It has spawned a plethora of devices and applications, such as headphones and headsets, printer connectivity, virtual dating and even certain viruses. High-end PDAs include Bluetooth, but some devices can add connectivity with a Bluetooth adaptor card that goes into one of the storage card slots.

WiFi

A PDA with WiFi connectivity can connect to the internet through the 802.11b/g specification which provides for transmission of data over the 2.5GHz band. PDAs with WiFi can connect to the internet for web browsing and emailing in hot spots or wireless internet zones both in Australia and overseas. WiFi connectivity can also be added to some PDAs through an add-on card if it isn't built in.

GSM/GPRS

Some PDAs now have GSM/GPRS connectivity for voice and/or data connectivity. A model with a slot for a SIM card can be used as a phone, while others can be used for data transfer through GPRS which provides for internet and POP3/IMAP email at speeds of about 56Kbps. It's also possible to use an adaptor card to provide GSM/GPRS functionality in PDAs that don't have this built in.

GPS

There are a small number of PDAs on the market that are also GPS devices and can be used for mobile connectivity and satellite-based navigation. They tend to be in the mid-range of devices, but still have good processing speed and storage space. In addition, a PDA with Bluetooth can use a Bluetooth GPS receiver for real-time mapping via GPS.

Multimedia

Many PDAs will now play MP3 music files, the most common music file format. Models with more onboard storage or a storage card slots are preferable if music playback is important, because MP3 files will use up a great deal of storage space on these devices. Small earphone or headphones will be needed for listening and devices with Bluetooth may be compatible with wireless headphones for added portability.

Some models include a microphone for voice recording personal memos or creating voice messages to send via MMS or email. This is a useful feature as it saves needing another device, but voice quality may be inferior against dedicated voice recorders and additional storage cards might be necessary for saving long or numerous messages.

Megapixel digital cameras are increasingly common in PDAs for business purposes, such as recoding locations, shop design or prototype objects, as well as personal uses like sharing baby photos or travel pictures. Many models have a 1.3MP camera onboard and, with larger screens and better resolution, they're good enough to make a small print or email to others. Video capture is also starting to appear in more models and as inbuilt storage and storage card capacity continues to grow, capturing better pictures and video will be possible.

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