Comparison of real-time operating systems

This is a list of real-time operating systems. An RTOS is an operating system in which the maximum time from an input stimulus to an output response can be definitely determined.

Name License Source model Target usage Status Platforms Official site
Abassi Proprietary closed embedded active AVR32, ATmega, Coldfire, Cortex-A9, Cortex-M0, Cortex-M3, Cortex-M4, MSP430, PIC32, TMS320C2000, 80251, 8051
AMOS Proprietary ? commercial closed 680x0, 683xx, x86 via emulation
AMX RTOS Proprietary closed embedded active 680x0, 683xx, ARM, ColdFire, MIPS32, PowerPC
uKOS GNU GPL open source embedded active Cortex-M3, Cortex-M4, 6833x, PIC, CSEM icyflex-1, STM32
ARTOS (Locamation) Proprietary closed power-system automation active x86
ARTOS (Robotu) Proprietary ? embedded, robots defunct ARM9+
Atomthreads BSD License open source embedded active AVR, STM8, ARM, MIPS
AVIX Proprietary closed embedded active Atmel AT91SAM3(U/S), Energy Micro EFM32, NXP LPC1300, LPC1700, ST Micro STM32, Texas Instruments LM3S, Toshiba TMPM330, Microchip PIC32MX, Microchip PIC24F, PIC24H, dsPIC30F & dsPIC33F
BeRTOS modified GNU GPL open source embedded active DSP56K, I196, IA32, ARM, AVR
BRTOS MIT License open source embedded active Freescale Coldfire V1, Freescale HCS08, Texas Instruments MSP430 and Atmel ATMEGA328/128 (Port for PIC18 in development
CapROS GNU GPL open source embedded active IA32, ARM9
ChibiOS/RT Modified GNU GPL or proprietary open source embedded, small footprint active x86, ARM7, ARM9, Cortex-M0, Cortex-M3, Cortex-M4, PowerPC e200z, STM8, AVR, MSP430, Coldfire, H8S
ChorusOS ? ? ? ? SPARC, x86, PowerPC
ChronOS GNU GPL open source research, general purpose active x86, ARM
CoActionOS Modified GNU GPL or proprietary open source embedded active ARM Cortex-M3, LPC17xx
cocoOS BSD License open source embedded active AVR, MSP430, STM32
Concurrent CP/M Proprietary closed (meanwhile: open source) general purpose, industrial defunct 8080, Z80, 8086 Digital Research
Concurrent DOS Proprietary closed general purpose, industrial defunct 8086, 286, 386, 68000, (also 8080/Z80 in dual-processor variants) Digital Research
Contiki BSD License open source embedded, WSN active MSP430, AVR
COS Proprietary closed process control defunct GEC 4000 series ?
CooCox CoOS BSD License open source general purpose active STM32, NXP LPC1000, TI LM3S8962,Nuvoton NU1xx,Holtek HT32
Deos Proprietary closed safety critical active x86, PowerPC, MIPS
DioneOS Proprietary available for licensee embedded active Texas Instruments MSP430, MSP430x
DNIX Proprietary closed general purpose defunct 68000 ?
dnx RTOS GNU GPL, modified GNU GPL, and BSD License open source embedded (Unix-like) active ARM Cortex-M3, STM32
GEC DOS Proprietary closed process control defunct GEC 4000 series ?
DSOS ? ? ? defunct TI-980A minicomputer ?
DSP/BIOS free closed, available with license general purpose maintenance only Primarily Texas Instruments C2800, C5500, C6000 and OMAP DSP cores. Replaced by TI-RTOS, but available for download.
DSPnano RTOS Open Source and Commercial Open Source MCU, DSC, DSP SoC active R8C, M16C, PIC24, dsPIC33
DuinOS Modified GNU GPL Open Source general purpose active Atmel AVR (Arduino)
eCos Modified GNU GPL open source general purpose active ARM/XScale/Cortex-M, CalmRISC, 68000/Coldfire, fr30, FR-V, H8, IA32, MIPS, MN10300, OpenRISC, PowerPC, SPARC, SuperH, V8xx
eCosPro Modified GNU GPL or eCosPro license open source with non-free portions general purpose active ARM/XScale/Cortex-A5/Cortex-A9/Cortex-M, 68000/ColdFire, H8/H8S, IA32, MIPS32/64/microMIPS, NIOS II, OpenRISC, PowerPC, SPARC, SH4/4A, TILE-Gx
embOS Proprietary closed embedded active 8/16/32 bit processors
Embox BSD License open source embedded active ARM, LEON, MicroBlaze, x86
Embkernel GNU LGPL open source embedded active ARM Cortex M
ERIKA Enterprise Modified GNU GPL + linking exception Open Source embedded active ARM7, ARM Cortex MX, Hitachi H8, Altera Nios2, Microchip dsPIC (including dsPIC30, dsPIC33, and PIC24), Microchip PIC32, ST Microelectronics ST10, Infineon C167, Infineon Tricore, Freescale PPC e200 (MPC 56xx) (including PPC e200 z0, z6, z7), Freescale S12XS, EnSilica eSi-RISC, Atmel AVR, Lattice Mico32, TI MSP430, Renesas RX200
EUROS Proprietary closed embedded active 8/16/32 bit processors: among others AVR, 8051, XC800, 16FX, XC166, ARM, Cortex-M3, PowerPC, Nios II, MIPS32, PIC32
EROS Modified GNU GPL open source experimental
research use 		dormant IA32
Femto OS GNU GPLv3 open source embedded active AVR
FlexOS Proprietary closed general purpose, industrial, POS defunct 186, 286, 386, V60, V70, 68000 Digital Research/Novell
FreeOSEK GNU GPLv3 open source embedded active Posix, Windows, ARM7
FreeRTOS Modified GNU GPL open source embedded active ARM, AVR, AVR32, Freescale ColdFire, HCS12, IA32, Cortex-M3, MicroBlaze, MSP430, PIC, PIC32, Renesas H8/S, 8052, STM32, EFM32
FunkOS modified Sleepycat License open source embedded active AVR, MSP430, Cortex-M3
Fusion RTOS free ? semi-general purpose active ARM, Blackfin, StarCore, DSP 56800E
HeartOS Proprietary closed safety critical active x86, PowerPC, ARM
Helium GNU LGPL Open Source Embedded Active Open-Source RTOS for HCS08 & AVR MCUs
HP-1000/RTE ? ? ? ? ?
Hybridthreads ? open source FPGA active Xilinx Virtex-II Pro ML310, Xilinx Virtex-II Pro XUP
IBM 4680 OS Proprietary closed general purpose, industrial, POS defunct 286 IBM (DR Concurrent DOS 286 derivative)
IBM 4690 OS Proprietary closed general purpose, industrial, POS active 286, 386 IBM (DR FlexOS 286/386 derivative)
INTEGRITY Proprietary closed embedded active ARM, XScale, Blackfin, Freescale ColdFire, MIPS, PowerPC, x86
IntervalZero RTX / RTX64 Proprietary closed MS Windows extension active x86 / x64
INtime Proprietary closed embedded active x86
ITRON, µITRON varies varies embedded active ARM, MIPS, x86, and others ,
ISIX GNU LGPL open source embedded active Cortex-M3
iRTOS GNU LGPL open source embedded active AVR, ARM7
KolibriOS GNU GPL open source embeddable active x86
Kithara RTS Proprietary closed general purpose, industrial active Windows extension, x86, x64, Windows 7/8
Lepton Mozilla Public License open source embeddable active ARM9 (ATMEL AT91SAM9261, AT91SAM9260), ARM7(ATMEL AT91SAM7x, AT91SAM7SE, AT91M55800), CortexM3 (ST STM32F103, Texas Instrument Stellaris) et CortexM4(Freescale KINETIS).
LithOS Proprietary ? embedded, industrial active LEON2/LEON3/LEON4, x86
LynxOS Proprietary source code available embedded active Motorola 68010, x86/IA-32, ARM, Freescale PowerPC, PowerPC 970, LEON
Mark3 BSD License open source embedded active, beta ?
MaRTE OS GNU GPL open source embedded active IA-32
MAX II,IV Proprietary ? ? ? Modcomp II,IV,... ?
MenuetOS GNU GPL open-source ? active IA-32
Menuet 64 Proprietary unknown ? active IA-32, x86-64
Micrium µC/OS-II Proprietary Available under license embedded active ARM7/9/11/Cortex-M1/3/4-A8/9, AVR, HC11/12/S12, Coldfire, Blackfin, Microblaze, NIOS, 8051, x86, Win32, H8S, M16C, M32C, MIPS, 68000, PIC24/dsPIC33/PIC32, MSP430, PowerPC, SH, StarCore, Renesas RX/RL, STM32, …
Micrium µC/OS-III Proprietary Available under license embedded active ARM7/9/11/Cortex-M1/3/4-A8/9, AVR, HC11/12/S12, Coldfire, Blackfin, Microblaze, NIOS, 8051, x86, Win32, H8S, M16C, M32C, MIPS, 68000, PIC24/dsPIC33/PIC32, MSP430, PowerPC, SH, StarCore, Renesas RX/RL, STM32, …
Milos GNU GPL open source embedded active Cortex-M3
mipOS Proprietary open source embedded active Cortex-M3, ST7, STM8, x86
Microsoft Invisible Computing (MMLite) Proprietary open source embedded active Arm7, Arm9, i386, h8, mips, Trimedia, eCog1
mLithOS Proprietary ? embedded, industrial active LEON2/LEON3/LEON4, x86
MP/M Proprietary closed (meanwhile: open source) general purpose, industrial defunct 8080, Z80, 8086 Digital Research
MQX Proprietary complimentary source code available embedded active Freescale Power, ColdFire, Kinetis Cortex ARM, List of Freescale products,
MERT ? ? ? inactive PDP-11 ?
Multiuser DOS Proprietary closed general-purpose, industrial defunct 386 Digital Research/Novell, Concurrent Controls/Datapac/IMS (see REAL/32)
Nano-RK mixed open source embedded, WSN active AVR, MSP430
Neutrino Proprietary some source code provided microkernel active ARM, MIPS, PPC, SH, x86, XScale
nOS Mozilla Public License open source embedded active AVR, MSP430, Cortex-M0, Cortex-M3, Cortex-M4, M16C, RX600, PIC24, Win32, Posix
Nucleus OS Proprietary source code provided embedded active ARM (Cortex-M3, M4, R4, R4F, A8, A9, ARM7, ARM9, ARM11), PowerPC, MIPS32, MIPS16e, microMIPS, Coldfire, SuperH
Nut/OS BSD License open source embedded, industrial active AVR, AVR32, ARM7, ARM9, Cortex-M3
NuttX BSD License open source embedded, small footprint active Linux user mode, ARM7, ARM9, Cortex-M0, Cortex-M3, Cortex-M4, 8052, SH-1, Renesas MC16C/26, Zilog Z16F, Zilog eZ80 Acclaim!, Zilog Z8Encore!, Z80, partial ports for MIPS
OpenEPOS Proprietary open source embedded active ARM, x86, AVR, MIPS, PowerPC
OS20 Proprietary closed embedded (STB) maintenance only ST20 ?
OS21 Proprietary source code provided embedded (STB) active ST40/SH4,ST200,ARM ?
OS4000 Proprietary closed process control maintenance only GEC 4000 series ?
OPENRTOS Proprietary source code available embedded active Same as FreeRTOS
OSA BSD open source embedded active PIC10-PIC24, AVR 8bit, STM8
OSE Proprietary closed general purpose active ARM, PowerPC, MIPS, IXP2400, TI OMAP, …
OS-9 Proprietary available to customers embedded active ARM/strongARM, MIPS, PowerPC, SuperH, x86/Pentium, XSCALE, Motorola 6809, Motorola 68000-series, SPARC
OSEK n/a specification embedded active engine control units
Partikle Proprietary ? embedded, industrial active LEON2/LEON3/LEON4, x86
Phar Lap ETS ? ? ? ? ? ?
PaulOS GNU GPL open source embedded ? ?
PICOS18 GNU GPL open source embedded ? PIC18 ?
picoOS Modified BSD License open source embedded discontinued 6502, 80x86, ARM7, AVR, PowerPC
Phoenix-RTOS Proprietary embedded ? ARM7, IA32, eSI-RISC
PikeOS Proprietary available to customers safety critical, virtualization active PPC, x86, ARM, MIPS, SPARC/Leon, SuperH
Portos Proprietary source code provided embedded, small footprint active (ARM soon)
POK BSD Licence open source embedded active x86, PowerPC, SPARC
PowerTV Proprietary ? ? ? ?
Prex BSD License open source microkernel active ARM, IA32
Protothreads BSD License open source general purpose active Architecture independent
pSOS Proprietary ? ? discontinued Motorola 680x, Motorola 68000 ?
QNX Proprietary ? general purpose active IA32, MIPS, PowerPC, SH-4, ARM, StrongARM, XScale
QP Open Source and Commercial Open Source MCU, DSC, DSP SoC active ARM7/9, ARM Cortex-M3/Cortex-M0, MSP430, TMS320C28x, AVR, AVRXmega, ColdFire, 68HC08, M16C/R8C, H8, 8051, 80251, PIC18, PIC24/dsPIC33, Nios II, PSoC1
Data General RDOS Proprietary ? general purpose defunct Data General Nova, Data General Eclipse n/a
ReaGOS Proprietary closed, available with license embedded active x86, ATmega, ARM, portable
REAL/32 Proprietary closed general-purpose, industrial active 386 IMS (Multiuser DOS derivative)
Real-time Linux (CONFIG_RT_PREEMPT) GNU GPLv2 open source general purpose active same as Linux wiki
REX OS Proprietary closed, available with license embedded inactive ARM ja:REX OS
RIOT GNU LGPL open source embedded active ARM, MSP430
RMX Proprietary closed embedded active 8080, 8086, 80386 or higher
RSX-11 Proprietary ? ? historic PDP-11 n/a
RT-11 Proprietary ? general purpose defunct PDP-11 n/a
RTAI GNU GPL open source general purpose active x86, ARM
RTEMS modified GNU GPL open source embedded active ARM, Blackfin, ColdFire, TI C3x/C4x, H8/300, x86, 68k, Milkymist SoC, MIPS, Nios II, PowerPC, SuperH, SPARC, ERC32, LEON, Mongoose-V
RTLinux GNU GPL open source general purpose inactive same as Linux n/a
RT-Thread GNU GPLv2 open source embedded active ARM, IA-32, AVR32, M16C, MIPS
RTXC Quadros Proprietary source available embedded active ARM - Atmel/Freescale/NXP/ST/TI, Blackfin, Coldfire/68K, PowerPC, StarCore, TI/Luminary Stellaris, TI OMAP, XScale
RTX Keil Real-Time Operating System Proprietary, royalty free source available embedded active ARM
RX116 ? ? embedded, industrial defunct NEC V20, NEC V30, NEC V40, NEC V50 first ITRON 1 compatible 16-bit RTOS
RX616 ? ? safety critical, embedded, industrial defunct NEC V60, NEC V70 32-bit ITRON compatible
RX-UX832 ? ? embedded, industrial, general-purpose defunct NEC V60, NEC V70 32-bit Unix-like RTOS
SafeRTOS Proprietary source code & Design Assurance Pack available embedded, Safety Critical active Same as FreeRTOS
SCIOPTA Proprietary closed, source available embedded, safety related active ARM, Cortex-M0, Cortex-M3, Cortex-M4, Cortex-R4, Cortex-A9, XScale, Renesas RX, PowerPC, ColdFire, HCS12, M16C, Windows(simulation)
scmRTOS free open source embedded active ARM, Cortex-M3, Blackfin, MSP430, AVR
SDPOS GNU LGPL open source embedded active ARM, Cortex-M3, Blackfin, PIC18, PIC24, i386 win32/linux synthetic targets
SHaRK GNU GPL open source ? ? ?
silRTOS free open source embedded active ARM, Cortex-M3 Cortex-A9 ARM-11MP, Blackfin, MIPS, AVR
SimpleAVROS GNU GPLv3 open source embedded active, beta AVR only n/a
SINTRAN III ? ? ? ? Norsk Data computers n/a
SOOS Project free open source embedded active, beta H8/300
Symbian OS Eclipse Public License open source embedded active ARM
Talon DSP RTOS Proprietary ? embedded DSP active TMS320
TargetOS Proprietary available to customers embedded ? ARM, Freescale ColdFire, Freescale PowerPC
T-Kernel free under T-License source available embedded RTOS active ARM/MIPS/SH/others
THEOS ? ? ? ? ?
ThreadX Proprietary available to customers ? active ARC, ARM/Thumb, AVR32, BlackFin, ColdFire/68K, H8/300H, Luminary Micro Stellaris, M-CORE, MicroBlaze, PIC24/dsPIC, PIC32, MIPS, V8xx, Nios II, PowerPC, SH, SHARC, StarCore, STM32, StrongARM, TMS320C54x, TMS320C6x, x86/x386, XScale, Xtensa/Diamond, ZSP
TI-RTOS Kernel (SYS/BIOS) BSD License open source embedded active Primarily Texas Instruments: MSP430, MSP432, C2000, C5000, C6000, TI's ARM families (Cortex M3/4F, Cortex R4, Cortex A8, Cortex A15), SimpleLink Wireless MCUs (CC2xxx, CC3xxx)
Trampoline Operating System (OSEK and AUTOSAR)GNU LGPL open source embedded active AVR, H8/300H, POSIX, NEC V850e, ARM7, Infineon C166, HCS12 or PowerPC
TNKernel BSD Licenses open source embedded active ARM, PIC24/dsPIC, PIC32, HCS08, STM32 (Cortex-M3)
TNeo BSD Licenses open source embedded active Cortex-M0/M0+/M1/M3/M4/M4F, PIC32/PIC24/dsPIC
Transaction Processing Facility Proprietary ? general purpose active IBM System/360 derivatives
TRON project open? mixed mixed active any: not an implementation, but a specification
TUD:OS GNU GPL open source ? active ARM, IA-32, X86-64
Unison RTOS Open Source and Commercial Open Source MCU, DSC, DSP SoC, FPGA active Pic32, ARM Cortex (TI Stellaris, ST STM32, NXP LPC1700), SH2A, SH2AFPU, R32C, MIPS4K, {SHARC, Coldfire, TMS320, Altera NIOS, Xilinx Microblaze, Proprietary}
UNIX-RTR ? ? ? ? PDP-11 ?
uSmartx BSD License open source embedded ? ARM7TDMI, AVR, H8
µTasker Proprietary Open-code. Free for non-commercial or with support license embedded active Freescale Kinetis, Freescale Coldfire M522XX, Atmel AVR32, Atmel SAM7X, TI Stellaris, NXP LPC2000, NXP LPC1700, ST-Micro STM32 (F1/F2/F4), ST-Micro STR91X, Freescale NE64, Windows (processor and peripheral simulation)
u-velOSity ? ? microkernel active ?
velOSity ? ? ? active Power Architecture, ARM/XScale, MIPS, x86/Pentium, ColdFire, Blackfin, OMAP, DaVinci
VRTX Proprietary ? ? superseded by Nucleus RTOS ARM, MIPS, PowerPC, RISC
VxWorks Proprietary ? embedded active ARM, IA32, Intel 64, MIPS, PowerPC, SH-4, StrongARM, xScale
Windows CE Proprietary Microsoft Shared Source embedded active x86, MIPS, ARM, SuperH
Xenomai GNU GPLv2 Open Source general active x86, x86_64, PowerPC, ARM, Analog Devices Blackfin BF52x, BF53x, BF54x and BF56x
XMK BSD License Open Source embedded inactive/beta ?
Simulink Real-Time Proprietary closed real-time testing/embedded active x86
Y@SOS GNU LGPL Open Source embedded active Cortex-M3, STM32
MontaVista Linux GNU GPL Open Source embedded active ?
µnOS ? ? ? historic Motorola 68k ?
uOS GNU GPL Open Source embedded active AVR, ARM, MIPS32, MSP430, Intel i386, Linux386