When moving from 8- or 16-bit microcontroller designs to the 32-bit ARM RISC architecture, one of the major items of concern will likely be the question of whether to use an operating system and, if so, what operating system to use.

Traditionally, many embedded designs are developed without the use of an underlying operating system. As applications become more complex, the project team often develops proprietary real-time operating systems (RTOS) or task schedulers. This article presents a background on the evolution of embedded operating systems and discusses how the move from 8- or 16-bit architectures to the 32-bit ARM processor-based devices affects the operating system decision.

The author discusses how the development of embedded operating systems moved from being an art to a science, looks at the evolution of commercial RTOSs, discusses the factors influencing operating system choices in the 32-bit RISC market, evaluates the invasion of traditional PC operating systems into embedded designs, and offers a short comparison of embedded operating systems popular in ARM processor-based designs.

Reprinted in its entirety from ARM IQ Vol. 4, No. 2, 2005