A microkernel-based operating system for personal digital assistants

There are a number of projects currently underway to create a new class of computing device called a personal digital assistant (PDA). These devices are hand-held computing systems that provide a range of applications including personal productivity, connectivity, entertainment and field data collection. One of the most important problems to be solved in developing practical PDAs is to provide a reasonable operating system for the application software that runs on the PDA. We believe that previous work on a microkernel using the Mach technology (D.L. Black et al., 1992) and operating system personalities provides the best foundation for such an operating system. Our microkernel offers modularity, a message-passing programming paradigm and real time features, all of which are important in a PDA operating system. Reusing the code developed for, or to run on our microkernel on a PDA also has obvious economic benefits. However, our standard microkernel and microkernel-based products require a number of changes to make them smaller and to adapt them to the PDA environment