Real-time operating system
A real-time operating system (RTOS) is an operating system (OS) intended for real-time applications. Such operating systems serve application requests nearly real-time. A real-time operating system offers programmers more control over process priorities. An application’s process priority level may exceed that of a system process. Real-time operating systems minimize critical sections of system code, so that the application’s interruption is nearly critical.
A key characteristic of a real-time OS is the level of its consistency concerning the amount of time it takes to accept and complete an application’s task; the variability is jitter. A hard real-time operating system has less jitter than a soft real-time operating system. The chief design goal is not high throughput, but rather a guarantee of a soft or hard performance category. A real-time OS that can usually or generally meet a deadline is a soft real-time OS, but if it can meet a deadline deterministically it is a hard real-time OS.
Currently the best known, most widely deployed, real-time operating systems are:
See the list of real-time operating systems for a comprehensive list.
Additional RTOS:
- BeRTOS
- FreeRTOS
- NuttX RTOS
- Open Kernel Labs
- TinyOS
- Jari OS
- Nut/OS is an intentionally simple RTOS for the ATmega128, which provides a minimum of services to run Nut/Net, the TCP/IP stack
- The Ethernut project is an Open Source Project for building Embedded Ethernet Devices
