DEC's early computers were for many years
restricted to laboratories

In August 2009, Unix operating system, celebrates its 40th anniversary, and it has been in use every year of those four decades. Work on Unix began at Bell Labs after AT&T, (which owned the lab), MIT and GE pulled the plug on an ambitious project to create an operating system called Multics. And in August 1969, Ken Thompson wrote the core of what became Unix. He allocated one week each to the four core components of operating system, shell, editor and assembler. It was during that time and after as the growing team got the operating system running on a DEC computer known as a PDP-7 that Unix came into being. The team got Unix running well on the PDP7 and soon it had a long list of commands it could carry out. The syntax of many of those commands, such as chdir and cat, are still in use 40 years on. Along with it came the C programming language.

Now Unix, in a variety of guises, is everywhere. Most of the net runs on Unix-based servers and the Unix philosophy heavily influenced the open source software movements and the creation of the Linux desktop OS. Windows runs the communication stack created for Unix. Apple's OS X is broadly based on Unix and it is possible to dig into that software and find text remarkably similar to that first written by Dennis Ritchie in 1971.

Source:→ BBC News