Real-time operating system

A real-time operating system (english real-time operating system, RTOS short ) is an operating system with additional real-time functions for the strict observance of time constraints and the predictability of the process behavior (hard real-time behavior ). The main component of such a specialized operating systems and real-time operating system kernel or short real-time kernel and general operating system kernel (English: kernel) called.

  • 2.1 micro-kernel
  • 2.2 Nano - kernel
  • Pico 2.3 kernel, Femto- kernel, Atto kernel, etc.

Requirements for real-time operating systems

Predictable Timing

While also common desktop operating systems can guarantee a soft real-time behavior for high priority processes, no hard real-time behavior can be accomplished by not exactly predictable time behavior by swapping, Heapzugriffe, hardware interrupts, etc., are guaranteed in worst- case scenarios.

Real time operating systems must, in contrast, can guarantee compliance with defined response times even in the worst case. This concerns mainly the areas scheduling and memory management.

Error detection

Real-time operating systems must support additional error detection mechanisms.

Common architectures

Micro kernel

In this architecture, the actual kernel runs as a task of lowest priority and the real-time kernel handles the scheduling. The real-time processes have the highest priority. This brings minimum latency with it.

Nano - kernel

Similar to the micro-kernel approach, however, there is the possibility to run any number of other operating system kernel in addition to the actual real-time kernel.

Pico - Kernel, Femto- kernel, Atto kernel, etc.

Are practically nothing other than nano- kernel, just want their developers turn out with ever lower SI prefixes in the name explicitly the minuteness of its kernel.

Examples of real-time operating systems

  • ADwin
  • ChorusOS by Chorus Systèmes S. A. / Sun Microsystems, various licenses
  • CMX -RTX CMX Systems, Inc. for various microcontroller
  • DRYOS or DRYOS is a real- time operating system from Canon digital cameras and camcorders
  • A free eCos real-time operating system for embedded systems
  • ERIKA ERIKA Enterprise RTOS OSEK OS is an open-source ( BCC1, BCC2, ECC1, ECC2 ), OIL, ORTI specifications for dsPIC, PIC32, AVR, Nios II, ARM7, S12XS, Tricore1, Mico32, PPC z7, cortex, esi RISC, MSP430.
  • FreeRTOS A free real-time operating system for various microcontroller
  • Libertos A free real-time Linux kernel
  • A unixoides LynxOS real-time operating system for critical applications primarily
  • MicroC / OS-II Real-time operating system, which is suitable for safety-critical systems.
  • MicroC / OS - MMU A real- time operating system with hardware technology supported memory protection and a guaranteed period.
  • Nut / OS real-time operating system of the open source project Ethernut.
  • On Time RTOS -32 A real- time operating system with Win32 -compatible programming
  • OS-9 Real-time operating system for control systems
  • Palm OS A real-time operating system designed specifically for PalmOne Pocket PCs
  • PikeOS A micro-kernel - based real-time operating system for safety-critical systems.
  • PowerPac from IAR Systems for various microcontroller
  • A unixoides QNX real-time operating system primarily for embedded systems
  • Real-Time Executive A real-time operating system for the Hewlett -Packard 1000 Series
  • Real VMX A VxWorks clones under LGPL
  • Rodos A real-time operating system, primarily for satellite applications
  • RT -11 A real-time operating system for the PDP-11 family
  • RTAI real-time extension for Linux
  • RTEMS Open source real-time operating system for multiprocessor systems
  • RTLinux uses modified kernel modules to give Linux real-time properties. Carrier Grade Linux
  • RTOS -UH A real-time operating system for automation technology
  • RTOSVisor parallel operation of a generally useful operating systems and RTOS
  • RTX and RTX64, real-time extensions for Windows Operating Systems
  • SCIOPTA RTOS for small to large and safety-critical systems
  • Smx RTOS for ARM, Cortex, PowerPC based microcontrollers from Digital Inc.
  • TTP - OS
  • VxWorks operating system certifiable
  • Windows CE real-time operating system from Microsoft for various architectures
  • Xenomai royalty free offshoot of RTLinux for embedded systems
Task (computing) HP 2100 Rodos (operating system) RT-11 Digital Object Identifier
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