Mobile computers come in different sizes and shapes, and they use different operating systems. The objective is to provide solutions for a variety of environments. Some of these options are summarized in Figure .

Some devices use an integrated wireless NIC, whereas others use one that is PCMCIA or CompactFlash card-based. There are three basic types of handheld devices. They are key-based, pen-based, and vehicle-mount. Handheld devices allow users to browse the web, access LAN resources, capture data real time, scan, and print. These devices are typically constructed to withstand harsh environments, unlike most laptop computers and PCs. Mobile computing is great for collecting, processing, and communicating information and data when and where it is needed. These devices also operate at all seven layers of the OSI model like laptops and desktop PCs. 

Key-based devices, are used for applications requiring manual entry of character data. Such devices have a full alphanumeric keyboard, as well as an LCD display. Key-based computers are found in many businesses including retail, warehousing, and shipping.

Pen-based devices utilize a pen-like stylus and typically do not have a keyboard or keypad. An example is shown in Figure . These devices are specifically designed for information intensive applications. They are very rugged and can go almost anywhere. These devices do not require typing on a tiny keypad.

Vehicle-mount mobile devices are intended for use on a motorized pallet jack, forklift, or mobile cart. Many of these devices can port to a bar code scanner. This enables operators to transmit and receive data to and from a remote server. They come in several varieties, including those with keyboards, menu-driven, and touch-screen displays.

Mobile Computing Operating Systems (OS)

Several operating systems are used on mobile computers. The primary ones, listed in Figure , include MS DOS, Palm OS, Symbian OS, Windows Compact Edition (CE), and Windows XP Embedded. DOS is a very basic and efficient OS that will run one program at a time. The other OSs will run multiple programs at once. The Palm OS is an OS that was developed especially for PDAs. Symbian OS is an open standard OS, licensed for use in many mobile computing devices and easily customized with third-party software. Windows CE and Windows XP embedded are simplified versions of Windows. Windows XP Embedded is only for use on x86 CPUs. The look and feel are very similar to that of the desktop Windows versions. An early version of Windows CE was called Pocket PC. Remember that the mobile computer must be interoperable with the desktop PC protocols, or additional software may be needed.

Other Mobile Computing Devices

The first phase of 802.11 compliant voice devices are now available. They include handheld devices from Cisco and Symbol. The second phase will support both data and voice on one handheld device, such as the Compaq iPaq. IEEE 802.11 voice products must be integrated with a server-based voice management platform such as the Cisco Call Manager. The Cisco Call Manager will be presented in the last section. The last section also covers the Cisco Architecture for Voice, Video, and Integrated Data (AVVID).

Mobile devices can be based on different wireless standards. It is important to use only 802.11 compliant devices. The big advantages in doing this include interoperability, speed, reliability, and real-time data communications. Equally important is choosing a software application package that will be compatible with the devices used in a given environment. Other considerations and concerns include battery life and durability. Some uses of mobile devices with third party applications will be discussed later in the course.

Web Links Symbol Technologies http://www.symbol.com  Microsoft Embedded OSs http://www.microsoft.com/ windows/embedded/  Palm http://www.palm.com