Unix & C
C is quirky, flawed, and an enormous success. ~ Dennis Ritchie
In the 1960s Dennis Ritchie and other AT&T programmers were working on scaling up Multics, a time-sharing OS, to handle thousands of users. The Multics project started as a cooperative project between MIT, GE, and Bell Labs (AT&T) in 1964 to develop a scalable time-sharing OS. Bell pulled out in 1969 because the project could not produce an economically useful system.
Ritchie and fellow programmer Ken Thompson, another Multics émigré, cast about for other work. Thompson got to developing a new file system for the PDP–7, the then-current DEC machine. Ritchie joined in.
Written in assembly language, their nascent OS was dubbed Unix by co-worker Brian Kernighan as a sarcastic reference to Multics.
When the PDP–11 came out in 1970, Ritchie put Unix on it by tweaking the old PDP–7 assembler for the new machine. Meanwhile, Thompson worked on B, a compiler-writing tool he derived from BCPL, which had been written by English programmer Martin Richards in 1966.
B and BCPL were essentially shortcuts for writing in assembly. B was typeless (without data types, except for a nondescript word), and so fell short of being a programming language like algol.
In 1972, Ritchie added data types to B to better support the PDP–11 architecture. Thus arose the language called C, which was imaginatively named by being the letter in the alphabet following B.
Ritchie then rewrote Unix in C; in the process beefing up C a bit by affording flexibility with data types and structures.
What came out of it was one of the first OS kernels written in a language other than assembly, and a language that hewed close to assembly while offering high-level constructs associated with structured programming. This spelled both efficiency and portability: a sure winner in the programming world. In the decades that followed C became the predominant programming language.
AT&T licensed Unix to outside parties from the late 1970s, leading to numerous variants of the OS.
Finnish American programmer Linus Torvalds wrote Linux for the prevalent Intel x86 chip architecture beginning in 1971. He started the project out of frustration about licensing restrictions on the Unix variant (minix) available to him at the time. Linux became a popular operating system with everyone from hobbyists to the supercomputing community because it was distributed gratis. Linux was also adopted by corporations, including IBM and Hewlett-Packard.
Apple ported its Macintosh operating system to Unix in 2002, its GUI a gloss over a proven bedrock. Apple did this after dissatisfaction with a native OS rewrite from assembly to C++, an object-oriented descendant of C.
The computing world runs on 2 basic operating systems: Windows and Unix. Android, the mobile-device OS developed by Google, is based on the Linux kernel.
