NCOS is the graphical user interface-based operating system developed for use in Oracle Corporation's Network Computers, which are discontinued. It was adapted by Acorn Computers from its own RISC OS, which was originally developed for their range of Archimedes desktop computers. It shares with RISC OS the same 4 MB ROM size and suitability for use with TV displays.
In 1999, Pace acquired the set-top box (STB) division of Acorn Computers,: 5 : 9 this being a component in the disposal of assets around the takeover of Acorn by MSDW Investment Holdings. This gave Pace the rights to use and develop NCOS. RISCOS Ltd later announced Embedded RISC OS, which was to have similarities with NCOS.