Rexx - Handheld & Embedded Programming

Handheld devices have come a long way and Rexx has a lot of ways in which it can run on these devices. Rexx has support for Pocket PC’s, Palm devices, PDA’s and other smart phone devices. The advantage of Rexx to work on these platforms is that Rexx is really a small weight programming system which just runs in the span of a few kilobytes.
Hence it becomes easier to run Rexx programs on these devices.
Rexx on handheld devices can run in the following modes −

• The first mode is the native node where it runs directly on the operating system itself. The advantage on running in this mode is that it is faster since it runs directly off the operating system.
• The next mode is on top of the DOS or emulator program on top of the hand held device. The advantage of this mode is that is can run on any type of operating system as long as the emulator runs on that operating system.

The Rexx Interpreters for the various hand held devices categories are shown below.

• Windows CE – Brexx
• Palm OS – Rexx for Palm OS
• Symbian OS - Regina

For the DOS emulator, the following steps need to be carried out −
Step 1 − First is to download PocketDOS which is a popular DOS emulator. It is designed to run on many operating systems and has support for common VGA screens and serial and parallel ports.
Step 2 − The next step is to download the BRexx files for 16-bit DOS to a Windows PC.
Step 3 − The final step is to use ActiveSync to sync the Rexx program to the handheld device.
There are some other commercial DOS based products available. XTM is a product which falls under this category. The features of this product are as follows −

• Support for the 80186 CPU and instruction set.
• It kind of works off the BIOS code for better performance.
• It can provide emulation for the Math co-processor, version 8087 MPU
• It provides access to the serial ports.
• It supports a variety of languages such as English, French and German.