Comparison of embedded operating systems?

Question

I've been involved in embedded operating systems of one flavor or another, and have generally had to work with whatever the legacy system had. Now I have the chance to start from scratch on a new embedded project.

The primary constraints on the system are:

• It needs a web-based interface.
• Inputs are required to be processed in real-time (so a true RTOS is needed).
• The memory available is 32MB of RAM and FLASH.

The operating systems that the team has used previously are VxWorks, ThreadX, uCos, pSOS, and Windows CE.

Does anyone have a comparison or trade study regarding operating system choice?

Are there any other operating systems that we should consider? (We've had eCos and RT-Linux suggested).

Edit - Thanks for all the responses to date. A pity I can't flag all as "accepted".

Answer 1

It all depends on how much time was allocated for your team has to learn a "new" RTOS.
Are there any reasons you don't want to use something that people already have experience with?

I have plenty of experience with vxWorks and I like it, but disregard my opinion as I work for WindRiver.

uC/OS II has the advantage of being fully documented (as in the source code is actually explained) in Labrosse's Book. Don't know about Web Support though.

I know pSos is no longer available.

You can also take a look at this list of RTOSes

Answer 2

I worked with QNX many years ago, and have nothing but great things to say about it. Even back then, QNX 4 (which is positively chunky compared to the Neutrino microkernel) was perfectly suited for low memory situations (though 32MB is oodles compared to the 1-2MB that we had to play with), and while I didn't explicitly play with any web-based stuff, I know Apache was available.