What RTOS have you used or recommend for 32-bit processors.
I'm interested in mainstream processors here: PowerPC, Pentium, ARM, MIPS
A link to a web site would be a nice bonus.
Let's conduct this as a poll. Please only provide one selection per answer and mod up if you agree with a selection already present.
VxWorks by Wind River is one of the major RTOS out there. See http://www.windriver.com/products/vxworks/
Linux is also making a strong showing in the embedded space. There are a number of vendors that provide packaged systems. See http://en.wikipedia.org/wiki/Embedded_Linux and also http://elinux.org/Main_Page
Depends what you want from a real time O/S
But Windows CE allows for hard real time.
We have used embedded uCLinux for embedded apps and control. But we also use Windows XP/Vista to do hard real time control down to 50ms response times.
QNX seem to be the one with the best library and tools. Well from what I heard from the guy responsible of that side of many projects I worked on.
This question is awfully vague, considering the range of 32-bit processors available nowadays. I've liked QNX in the past on a 933MHz Pentium-3 with 512MB of RAM, and I'm using FreeRTOS now on a 72MHz ARM Cortex-M3 with 64kB of RAM. Both suited their purposes very well.
Open, good performance, multiple platforms supported - RTEMS from Oarcorp (http://www.oarcorp.com/)
Also, depending on your hardware, eCos (http://ecos.sourceware.org/) is worth a look.
I can recommend ThreadX from Express Logic (http://www.rtos.com/). I've used it with some success on an ARM7 processor.
MontaVista (http://www.mvista.com/) provides a real-time version of Linux that can run on a wide variety of platforms. It can support response times as low as 30 us.
OpenSolaris is a modern RTOS, works on 32-bit architectures, and has some good tools as well. Congrats on Sun making the right decision and opening up Solaris!
FreeRTOS (www.FreeRTOS.org) runs on many micros and it's free, open source, and it can be used in commercial applications. There are many demos for various MCUs on their web site. One place it is used is the firmware for the Make Controller board (http://makezine.com/controller) which uses a AT91SAM7X ARM7 micro.
We are using Keil's RL-RTX RTOS for ARM MCU.
Contrary to Keil's reputation in 8051 world, their ARM development tools has been changed deeply, after ARM corporation has acquired them, and the quality is still suffering from this dramatic change.
The RTOS still has critical bugs, and the package they sell with it (RL-ARM. Including A Flash file system, TCP\IP stack, USB stack and CAN stack) is not well designed totally not ready for multitasking environment.
Sorry about the negativity, but after paying much of money, I expected for more from senior, well-known company (now own by big ARM).
I can recommend Green Hills INTEGRITY (http://www.ghs.com). I have used it on safety-critical systems based on ARM architectures. The tools are very good (IDE, debugger, performance analysis, event logger, jtag probe) and the support is good as well. It's royalty-free which means that the tools and support are pricey but if you have a safety-critical system it's well worth it.
I can second the vote for ThreadX. Here is a link to an article that discusses it's relative popularity, and provides a graph of how well used various RTOSs are:
Interestingly missing from the above:
Enea OSE, which is very common in telecom core network equipment and hundreds of millions of feature phones (the SonyEricsson walkman, cybershot, etc. series, and also I think Samsung).
IAR PowerPac, a very simple cheap basic task scheduler.
In my mind, an RTOS is an OS that is not trying to be average-case best-effort but have some more hard ways to make sure certain things get done and not others. And short interrupt latencies sometimes.
If you want to use it as a realtime OS, you'll need plugins though.
QNX has been mentioned, but erroneously as a x86 specific product. QNX-Neutrino is cross platform.
QNX's Microkernel architecture uses MMU protection capabilities to provide extremely robust and fault-tolerant systems. In most commercial RTOS's MMU protection is an add-on, and the user selects what is protected. In QNX everything is protected unless the user decides to expose I/O or memory to specific tasks.
Mentor Graphics' Nucleus
Only because it has not yet been mentioned. No direct experience, but is usually on my short-list when RTOS selection time comes around.