Linux sets its sights on the PDA market
In recent months there have been numerous announcements of new Embedded Linux support for PDAs and other handheld personal computing devices. Additionally, a growing number of PDAs (and similar devices) are known to be in development that will offer Linux as their primary embedded operating system.

Given the rapid emergence of Embedded Linux as a major "third alternative" to Palm OS and Microsoft Windows CE for handheld personal computing devices, LinuxDevices.com has created this Linux-PDA and PDA-Linux Quick Reference Guide, which will provide a continually updated overview of available and developing Linux-based PDA support.

The information in this guide is divided into three categories:
--PDAs that use Linux as their internal operating system
--Linux-based operating system packages that support multiple  PDAs
--Articles for further reading

While there are rumors of many new Linux-based PDAs being developed, here are several that have already been announced...

Invair Filewalker
Invair Technologies (Stuttgart, Germany) unveiled a new Linux-based PDA at CeBIT 2002 in Hannover, Germany. The device was designed to be operated with one hand, weighs a mere 0.2 lbs, and is small (though somewhat thick), at 3.4 x 2.2 x .74 in. It's based on an Intel StrongARM processor clocked at 133MHz and includes 32MB SDRAM and 16MB Flash ROM, has a 160 x 240 pixel grayscale LCD display, and provides IrDA and USB interfaces plus an expansion slot for SD and MMC cards.

Royal Lin@x
Royal Consumer Information Products unveiled a new Linux-powered PDA at CES in Las Vegas, NV in January, 2002. The device is based on a 206 MHz Intel StrongARM processor with 32MB system RAM and 16MB built-in flash storage. It has a full-color 320 x 240 pixel TFT LCD with touch panel, and is equipped with a CompactFlash expansion slot, USB, IrDA, and an RS232 serial port. The device's software stack is based on Century Software's PIXIL PDA software suite, which includes the Microwindows GUI.

Sharp Zaurus SL-5000
Sharp's new PDA for the worldwide market features an embedded Linux OS supplemented by a Java application environment. The device is based on a 206 MHz Intel StrongARM processor with 32MB system RAM and 16MB built-in flash storage. It has a full-color 320 x 240 pixel TFT LCD with touch panel, plus a built-in QWERTY keyboard (located behind a slide cover), and is equipped with CompactFlash and SD-card slots, IrDA, and USB interfaces. The device's software stack is based on Embedix Plus PDA, which includes Lineo's Embedix embedded Linux, Trolltech's Qt/Embedded GUI application framework, Opera's Opera 5 for Linux web browser, Insignia's Jeode PDA Edition (a Sun-authorized Virtual Machine that is compatible with the PersonalJava specification), and Trolltech's Qt Palmtop user interface and application suite.

Agenda VR3
The VR3 is a full-function PDA with a 160 x 240 pixel (2.25" x 3.25" viewable area) backlit LCD. It is based on a 66MHz 32-bit NEC VR4181 processor, and has 8 MB of system RAM and up to 8 MB of built-in flash storage. The built-in flash memory prevents data loss due to a discharged battery condition. The device has a standard RS232 serial port plus a special high-speed serial port, along with an IrDA interface. Its operating system is Linux-VR.

G.Mate Yopy
The Yopy integrates the functions of Internet and email access (via mobile phone), digital voice recorder, MP3 (audio) and MPEG (video) player, video games, plus a full set of PDA applications--all within a compact PDA-sized package. Besides containing a genuine Linux operating system, the device boasts a 4-inch full-color backlit LCD screen, does its computing business with a "powerful" 206 MHz 32-bit Intel StrongARM processor, provides both RS232 serial and USB expansion interfaces, and offers a CompactFlash Type II (CF-II) socket for memory or I/O expansion.

Compaq iPAQ
Though not natively equipped with Embedded Linux, there are now multiple projects to develop Linux implementations for the iPAQ, including one from the Compaq-sponsored handhelds.org site. The iPAQ has a 240 x 320 pixel backlit color LCD screen and is powered by a 206MHz Intel StrongArm processor with 32MB of RAM and 16MB of flash memory. External interfacing and expansion are via IrDA, serial (sync/async), USB, and PCMCIA. Multiple sources of Embedded Linux support for the iPAQ are provided in the next section of this guide (below).

HanGil C3224 multimedia PDA
Based on a 206 MHz 32-bit Intel StrongARM SA-1110 system-on-chip processor plus 16MB RAM and 16MB Flash. The display is a 3.8-inch full color Quarter VGA (240 x 320 pixel) TFT LCD, with touchpad, and the device offers built-in USB, IrDA, and RS232C interfaces along with CompactFlash expandability.

MasterIA PDA
Like many recently introduced PDAs, this device is based on Intel's 206MHz StrongARM SA-1110 system-on-chip processor, and has a full-color 320x240 pixel TFT LCD screen plus expansion slots for CompactFlash Type II and SmartData (SD) cards. Internal resources include 32MB RAM for program operation, and either 16MB or 32MB of Flash memory for program and data storage.

CIIT multimedia PDA
Based on an Intel 206 MHz StrongARM SA-1110 system-on-chip processor with 32MB of DRAM and 32MB of Flash storage memory. I/O connections include USB, serial, and Ethernet ports, and there is a CompactFlash slot for additional expansion (memory or I/O). The display is a 240 x 320 pixel, 4096-color LCD.

Empower PowerPlay III
The PowerPlay III PDA is manufactured in Taiwan and sold online by Empower Technologies, a vendor of Embedded Linux for intelligent appliances. The device is claimed to be Palm IIIxe compatible, from a hardware perspective. But unlike Palm's PDAs, the PowerPlay III runs Empower Technologies' Linux DA O/S implementation of Embedded Linux for the Dragonball processor.

HNT Exilien
The new Linux-based HNT handheld multimedia PCs will be made in two form-factors--a PDA-sized unit with a 3.8-inch 320x240 LCD, and a heftier sized device (one inch thick) with a backlit 4-inch TFT 640x480 LCD. The larger unit differs from the smaller one in several features, including LCD type, memory capacity, and type of expansion card slot. Both are based on a 206 MHz 32-bit Intel StrongARM SA-1110 system-on-chip processor along with a generous supply of DRAM and Flash memory.

MiTAC CAT
The Linux-based CAT will initially be available only in Taiwan. The device is based on a 66 MHz NEC VR series processor with 8MB system memory and 4MB Flash, expandable via a CompactFlash slot. It has a 4.1-inch, 240 x 320 pixel, monochrome backlit STN LCD with and provides multiple connectivity options including IrDA, RS232, USB, and Bluetooth.

VTech Helio
Though not natively equipped with Embedded Linux, there are several implementations of Linux for the Helio in development. The device is based on a 75 MHz 32-bit RISC processor, with 8 MB of SDRAM and 2 MB Flash memory. It has a 160 x 160 pixel backlit LCD display with a 1024 x 1024 cell touchpad, integrated audio record/playback, and both standard and high-speed serial ports.

4P DAT500
A rugged handheld--this is an industrial strength handheld computer, intended for use in mobile point-of-sale and inventory management applications. In addition to all the expected functions of a consumer palm-top computer (graphical user interface, touchscreen, handwriting recognition), the DAT500 is highly rugged and reliable, and has successfully passed testing for compliance with commercial aviation safety standards. The unit includes a built-in bar code scanner, credit card reader, smartcard interface, and printer.

SK Telecom IMT2000 WebPhone
This device is a combination cell phone plus PDA. It has a 4" LCD screen and a built in video camera, and looks like a PDA. The PDA functions of the device are based on a StrongARM SA1110 206MHz CPU, and the device contains 32MB of RAM plus up to 32MB of internal flash memory. The operating system software is PalmPalm's Tynux embedded Linux, with Qt/Embedded for GUI support plus Opera's browser. A separate microprocessor controls the cell phone functions.

There are currently three publicly announced "commercial" implementations of Embedded Linux for PDAs and other handheld devices. There are also two "non-commercial" offerings--one from handhelds.org, a website established by Compaq to promote the use of Linux on handheld devices, and another related project known as "The Familiar Project". There's no doubt that there will be more PDA Linux offerings announced in the near future...

Qt Palmtop Environment
Trolltech describes their Linux PDA support as follows: "The Qt Palmtop Environment is a complete Window System, Window Manager, Application Launcher, Input Methods (virtual keyboard, etc.), commercial-grade GUI toolkit, and a collection of useful applications, all written using the standard Qt API--the same API found on Qt/X11 and Qt/Windows. But because the Qt Palmtop Environment uses Qt/Embedded, there is no need for an X11 server, no extra client libraries, no separate window manager, no layer-upon-layer of toolkits--Qt/Embedded works directly with the Linux framebuffer. The applications include an Address Book, Date Book, File Browser, HTML Help Browser, Text Editor, Todo List, MPEG Video and Audio Player, a Calculator, Clock, Tetr*x game, Solitaire, Memory and Load Meter, Screen Rotator, plus a non-plush toy Tux! All that in under 2.5MB."

PIXIL PDA operating environment
Century Software describes their PDA Linux support this way: "The PIXIL PDA suite offers a complete PDA system including an Operating Environment, a full set of PIM applications, and extras you wouldn't expect including an e-mail client, web browser, and a set of multimedia applications. The Microwindows graphical windowing system is at the core of the PIXIL PDA solution."

PocketLinux PDA Framework
This Linux-based PDA software environment from Transvirtual Technologies, integrates Kaffe (a "clean room" implementation of Java) with a Transvirtual-developed implementation of Embedded Linux, and also provides built-in support for XML. PocketLinux also includes an integrated framebuffer graphics library that eliminates the need for a resource-hungry X Window System. Transvirtual characterizes their PocketLinux PDA Framework this way: "PocketLinux allows developers to write mobile applications as easily as they now create Web pages, and allows users to access any applications and data on any PDA or other handheld platform. The result is the ability to run the same applications on any PDA running PocketLinux, regardless of hardware. Users can create personal information networks (PINs) that give them the information they want, when, where, and how they want it."

handhelds.org PDA support
Want to create your own unique Linux PDA implementation? handhelds.org is for you! Early this year, Compaq created the Open Handheld Program, an initiative designed to stimulate innovation and research on handheld devices that resulted from the company's "Itsy" pocket computer project. To support this initiative, Compaq created handhelds.org--a vendor neutral website dedicated to open source handheld development. Not surprisingly, Compaq's iPAQ PDA is used as the base platform for all these activities and, consequently, a iPAQ Linux port is available as freely available open source software.

The Familiar Project
This open source PDA Linux project, which is an offshoot of the activities at handhelds.org, has collected together all of the key components of a complete Linux-based PDA computing platform. As of this writing, the Familiar distribution includes a Blackbox-based window manager, Agenda Computing's Fltk+ based PIM applications, an embedded Python implementation, system configuration and settings backup utilities, OpenSSH client and server, and a Debian-based ARM kernel.

This popular LinuxDevices.com article series explores the history, status, alternative architectures, and future developments of Linux on PDAs and handheld devices. In this series, we investigate various Linux PDA environments in detail, examining their ease of installation, cross-development, and use. Be sure to read them all.

Part 1: Exploring Linux PDA software alternatives
This article is the introduction to the series and provides an overview of three currently available PDA Linux distributions.

Part 2: Hacking the iPAQ with Linux, for fun and profit
In this installment, we prepare for future exploration of three "off-the-shelf" iPAQ PDA distro's, by obtaining, installing, and testing the "generic" iPAQ Linux support from handhelds.org.

Part 3: Installing Microwindows on the iPAQ
This installment explains how to download, install, configure, and test the Microwindows Development Toolkit by Century Software. Learn how to install the full X-based simulation of the iPAQ ScreenTop environment on your desktop Linux box--that way, you can develop and run iPAQ apps while you're waiting for your iPAQ to arrive (or if you aren't ready to buy one)!

Part 4: Installing the Qt Palmtop Environment on the iPAQ
In this installment, we learn how to download, install, configure, and test Trolltech's Qt Palmtop Environment (QPE), and what it's like to develop handheld apps using QPE.

Part 5: A developer's perspective on PocketLinux
In this installment, we learn about the architecture, environment, and programming techniques used to develop applications with the Transvirtual Technologies PocketLinux PDA framework.

Part 6: A developer's perspective on Agenda's VR3 Linux PDA
In this installment, we take a close-up look at the new Agenda VR3 Linux PDA, from both a user and developer point of view.

Other articles of interest include:

An interview with IBM's Linux Wrist Watch project leader
The project leader of the IBM Linux Wrist Watch project discusses the goals and objectives of the project--which was, basically, to see if Linux could be embedded into a device as tiny as a wrist watch. Did they succeed?

My Linux is smaller than your Linux
This comparison of several small-footprint implementations of Linux, while by no means exhaustive in its review of available implementations, provides a good indication of what is possible.