What operating system(s) do not use virtual memory?

[klover]

I am wondering if there are any operating systems that do not use virtual memory. Does anyone know of an OS that doesn't? I am asking because it has come up in a class and I haven't been able to find out if there are or not. I am assuming there is an Os or has been an OS that did not use virtual memory but I could be wrong. Does anyone know? Thanks.

 

[Greeko85]

Top of my head MS DOS. I'm sure there's others

 

[Someone Somewhere]

You can configure most OSs not to use virtual memory, and I'm sure you can e.g. compile the Linux kernel without support for it.

I think you'd have to get into embedded OSs to find one that can't use it at all, though.