he Rosicrucian Egyptian Museum in San Jose, CA displays clay tablets used by ancient Babylonians to record information. These tablets are nearly identical in size to the modern PDA. In light of this, it should not be a surprise that the convenient size of the PDA is one of the primary reasons the devices have been so rapidly accepted by today's workforce.

With relentless technology advances, the convenient size of the modern PDA can now provide the hardware power in the PDA comparable to that of desktop, and even some server machines of a few years ago. Battery technology has also made advances—although surprisingly less rapid than other PDA components—making the current crop of PDAs able to solve an ever wider variety of problems.

Editor's Note: On July 12, 2002, InfoWorld reported significant security vulnerabilities in the Sharp Zaurus. While this vulnerability has no relevancy to the content and techniques provided here, we recommend that Zaurus developers read about this vulnerability. Updated August 9, 2002: Sharp has since posted a patch for this vulnerability at myzaurus.com.

To demonstrate the Java performance improvements realized with today's PDAs over the last five years, Table 1 shows the time differential of two platforms when transferring 850 bytes from a modem (AT&V command) and displaying it in a Java TextArea. Note that enhancements to Java technology play a more significant role than the increase the CPU performance. Performance will continue to improve with the enhancements in processing power of PDAs. Some companies have announced they will ship PDAs based on the XScale CPU operating at 400MHz this year. In addition to faster hardware Java 1.4 also provides significant performance improvements that should make their way into PDA implementations of Java.

The performance improvement achievable with today's faster hardware can be seen in this table, which shows a simple benchmark for the transfer of 850 bytes from a modem and then displaying it in Java TextArea.

CPU	OS	JVM	Receive & Display (ms)
100MHz SH3	Wince 2.0	J++ 1.1	173000
206MHz SA1110	Linux (2.4 kernel)	Jeode	933

In spite of PDA advances, developing software for PDAs has traditionally been a relatively restricted exercise (compared to desktop development), often limited to using C/C++ that is tightly integrated with the PDA OS to ensure sufficient performance for end user applications. In concert with hardware advances, Java technology has made strong advances, making the PDA a remarkably suitable platform for development and deployment of Java applications.

This article discusses Java development on the recently released Sharp Zaurus SL-5500 PDA, and provides information regarding Java development on PDA devices in general. With the excellent performance of today's PDAs, developers can leverage their Java knowledge, and much of their existing Java object libraries, to deploy great functionality on a range of portable devices.