KolibriOS is an open source operating system with a monolithic preemptive, real-time kernel, video drivers, for 32-bit x86 architecture computers, developed and maintained by The KolibriOS Project Team. KolibriOS is a fork of MenuetOS, written entirely in assembly language. KolibriOS also known as KOS Its an worlds smallest OS of 3.4MB in size. you can download it by visiting there KolibriOS Official Website. Current KolibriOS 0.7.7.0 release introduces several kernel, applications and libraries updates.