A small team of researchers at Bell Labs released the first version of the UNIX computer operating system in 1969 in an effort to build a reliable programming software that could run on multiple platforms. Its openness and flexibility made it a key platform driving the development of computer hardware, software, and data networks in the past four decades.

UNIX emerged from a frustrating status quo in the computer science of the 1950s. Computers were not interoperable. Even within the same company, different computer lines often needed interpreters to communicate with one another. Computers also lacked flexibility. Operating systems were customized for each machine and, sometimes, each task. If a company wanted to upgrade its computer systems, it might need to create an entirely new operating system, which would have to be tediously reprogrammed with all of the old data.

In 1965, a team of computer scientists from Bell Labs and General Electric partnered with researchers at MIT to design the Multics (Multiplexed Information and Computing System) mainframe. This time-sharing system would be scalable, upgradeable, and capable of supporting many users, but it proved to be too expensive to sell on the market.

Hoping to create a more affordable platform, a small group at Bell Labs, which included Ken Thompson, Dennis Ritchie, Doug McIlroy and J.F. Ossanna, began work on UNIX in 1969. UNIX operated on a set of operational principles, including the use of plain text to store data, the organization of files hierarchically, and the development of “pipes” that connected data processes to achieve a specific output.

The founders of UNIX began the project on a PDP-7 computer, which Ken Thompson had been using to design and play a game, “Space Travel,” that took advantage of the machine’s top-notch display terminal. Through designing this game, Thompson and Ritchie gained programming skills necessary to operate a PDP-7. Through a series of meetings and drafts in the summer of 1969, Thompson and Ritchie created a set of processes for an operating system, including a command interpreter and the ability to copy, print, delete, and edit files.

In 1970, Thompson and Ritchie convinced their research department heads to invest in a new computer, the PDP-11, which had far more capacity for developing UNIX than the PDP-7. As they transferred UNIX between the computers, they developed a tool for text processing, which had an eager customer in the Bell Labs Patent Department. UNIX soon caught on at Bell Labs, as its groups recognized the value of the software as a workspace. The operating system became simpler to use in 1972, when Thompson and Ritchie converted its programming language to C.

In the mid-1970s, the popularity of UNIX spread, as the platform was released to academic institutions through inexpensive licenses. Later versions were sold to commercial and government organizations in the 1980s. By the end of the decade, the so-called “UNIX wars” broke out. One group of commercial licensees, AT&T and Sun Microsystems, tried to unify various iterations of UNIX into one system. In response, the Open Systems Foundation formed in 1988 to demand an “open” UNIX. In the end, two versions of UNIX survived.