Contiki is a small open source, yet fully featured, operating system developed for use on a number of smallish systems ranging from 8-bit computers to embedded microcontrollers, including sensor network motes. The name Contiki comes from Thor Heyerdahl's famous Kon-Tiki raft.
Despite providing multitasking and a built-in TCP/IP stack, Contiki only requires a few kilobytes of code and a few hundred bytes of RAM. A fully fledged system complete with a graphical user interface (GUI) will require about 30 kilobytes of code memory.
The basic kernel and most of the core functions are developed by Adam Dunkels.
A full installation of Contiki includes the following features:
Multitasking kernel
Optional pre-emptive multitasking (on a per-application basis)
TCP/IP networking
Windowing system and GUI
Networked remote display using Virtual Network Computing (VNC)
Web browser (claimed to be the world smallest)
Personal webserver
Simple telnet client
More applications are developed constantly. Known planned developments include:
an email client
an IRC client