The Linux implementation
The Linux version of the DAT500 makes use of an 8 MB Flash ATA PCMCIA card, on which the Linux files are stored.
Currently, the Linux version first boots DOS, and then the Linux kernel is launched from the Flash card. The final version of the system will eliminate the two-step boot process, booting Linux directly.
4P developed the Linux support for the DAT500 by themselves, starting from Caldera Open Linux 2.3 and currently using Linux kernel version 2.2.10. Display management is based on OpenGUI. Microwindows was also tested, but its performance was found to be too slow on the 386-level processor. No other Linux software components are currently offered, but a web browser will be added to the system at the time wireless connectivity is added.
The main Embedded Linux challenge, according to Silvano Mansutti, managing director of 4P Mobile Data Processing, was to come up with the appropriate graphics screen management software. The project began by studying Microwindows. However, the performance of Microwindows was inadequate on the system's 33 MHz Elan SC300 386-class processor. Given the project's tight schedule constraints, the development team decided to switch to OpenGUI, which appeared to provide much better performance.
Another challenge, in attempting to embed Linux, was the system's extremely limited memory resources (4MB RAM, 512KB Flash). However, that was easily overcome through the use of an ATA Flash PCMCIA card from which Linux is loaded.
Why embed Linux?
"We selected Linux as the operating system," says Mansutti, "because, as a hardware manufacturer, we wanted to offer our customers a product capable of supporting the best available application software solutions. Linux is growing very quickly, is stable, and is open source. As a result, more and more solution providers are migrating to Linux, and we wanted to be ready to support them."
"What we like very much about Linux is that it really offers an excellent performance/hardware-resource ratio, which in the hand-held products industry is currently still the weakest point of Windows CE," observes Mansutti. "Last, but not least: Linux is free."
"Our plan is to make the sources to our Linux port available as soon as we reach the final stages of development," adds Mansutti. "Our prediction/expectation is that Linux will become the only real alternative to Windows CE in industrial grade handheld computers."
