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Our Expertise:
A PDA (Personal Digital Assistant) is intended to replace the filofax for holding business
contact information and schedules on the go. These electronic devices have been around for years, with the first
models being simple address books which held names and phone numbers in a small electronic devices. PDAs have come
a long way since then, and today they include Word Processing, Spreadsheet, Presentations, E-mail, Music Players and
much more. Most modern PDAs use an LCD screen for both input and output, so the screen is in fact a touchscreen, which
can be used using a stylus (a small thin pen which is used to point at items on the screen).
The PDA has many components a normal computer does, and some more to boot:
- Microprocessor
- Operating System
- Solid-State Memory
- Batteries
- LCD Display
- Input device (keyboard/touchscreen/buttons)
- Input/Output ports
- Desktop PC Software
PDAs can be broken down into two categories: Hand-held computer and Palm-size computers. Although you may think
that both these devices would be extremely similar, they have many important differences. Hand-held computers tend
to be larger and heavier than Palm-size PDAs. However, they hold an advantage in that they boost a larger, clearer
display and use a miniature keyboard in conjunction with a touch-screen display. Palm-size computers rely on the
stylus and touch-screen technology using hand-writing recognition software for data input.
PDAs use a smaller, cheaper microprocessor than the ones found in regular desktop PCs and notebooks. Examples of
these processors are Motorola's Dragonball, Multiprocessor without Interlocked Pipeline Stages (MIPS) or Hitachi's
SH7709a. Although these processors tend to be far slower than those used in PCs (16-75MHz as opposed to around 2GHz),
they are perfectly ample for the tasks that the PDAs perform. The benefits of small size and price outweigh the
cost of slow speeds.
The Operating Systems used by PDAs are also different to those used by regular desktop and notebooks PCs. Operating
Systems for PDAs are far smaller in size (Palm OS is about 100K, about 1% of the size of Windows 98), and perform
less functions than a regular OS. The two most popular operating systems for PDAs are Palm OS (developed by 3Com) and
Pocket PC (Microsoft's Hand-held Windows equivalent OS). Pocket PC eats much more memory than Palm OS, but provides
much better integration with Windows applications through its mini Office-compatible suite of tools.
A PDA does not have a hard drive. It stores its application software in ROM (Read-Only Memory), which is not deleted
when the system is shut down. Data and user-installed programs are stored in the device's RAM (Random Access Memory),
which has several advantages over methods used by conventional PCs.
When you turn on the PDA, all your programs are instantly available. You don't have to wait for applications to load.
When you make changes to a file, they're stored automatically, so you don't need a Save command. And when you
turn the device off, the data is still safe, because the PDA continues to draw a small amount of power from the
batteries.
All PDAs use solid-state memory; some use Static RAM and some use Flash memory. Some are even incorporating removable
forms of memory. PDAs usually come with 2 MB minimum of memory. One megabyte of memory can store up to 4,000 addresses and
100 e-mail messages. However, many application programs take up memory space, so more advanced models usually have more
memory (5 to 32 MB). Also, PocketPC takes more memory space so PDAs with this operating system usually have 16 or 32 MB. In
some PDA models, the amount of memory is upgradeable.
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 what you
use it for. Here are some of the things that can drain batteries:
- Operating System - Pocket PC eats battery life because it takes up more memory
- More memory
- Colour LCD Display
- Voice Recording
- MP3 Player
PDAs have some type of LCD 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. Hand-held computers generally have larger screens than palm-sized computers. PDA
displays have the following features:
- LCD, enhanced LCD or colour super-twist nematic (CSTN) types
- Pixel resolutions (160x160, 240x320)
- Black-and-white (16 grayscale) or Colour (65,536 colours)
- Passive or Active Matrix - Active Matrix displays have sharper images that are easier to read
- Reflective or Back Lit - Backlit screens are good for reading in low light
PDAs differ greatly from desktop and notebook PCs in that they use other means of input devices than keyboards and
mice. Most PDAs have a touchscreen LCD display which is operated using a stylus (a small plastic pen which is used
to press items on the screen). Some PDAs use this stylus for word processing applications through the use of
hand-writing recognition software. Others include miniature keyboards (either on-screen or below the screen) for data
input. Some PDAs even include voice-recognition technology.
PDAs are one of the most useful creations since the notebook computer. They allow you to organise your life, carry
around documents and much more, on the move. Their growth is only just beginning and soon they will be standard
devices in a business person's briefcase. You can purchase various Sony CLIÉ PDAs from us at JL.com, along
with several accessories to accompany it.
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