Mainly windows. You can actually see other OS's being 'smoked' on a Microsoft video that bets $100 on this.
Symbian OS
samsung
O2
Do you mean the chipset, platform etc.,?
IOs
the fastest phone is the#1 htc hunderbolt it runs on the 4g lte network from verizon.
cell phones
Nexus phones use Android OS. Unlike most Android phones, the Nexus line are considered "pure Google" phones as the OS does not have either manufacturer and/or carrier modifications (in the form of "skins" and proprietary apps). They also typically receive software updates ahead of carrier phones.
you can update blackberry OS
Sony uses Android OS in its Xperia series mobile phones http://sonymobilephones.com/
iOS, Android, Symbian, BlackBerry OS, Palm OS, Firefox OS, Bada, Windows Phone, Web OS, embedded Linux, Ubuntu, Tizen.
If your talking about a computer, you will need to get an emulator but there aren't any emulators for emulating nokia phones for computers. For normal phones, you have to get the phone with the OS already installed, unless you have the ISO (OS files) and you are transferring it onto a device that will somehow download it, which probably you can't do..so......yea.