History of C (programming language)
The
origin of C is closely tied to the development of the Unix operating
system, originally implemented in assembly
language on a PDP-7by Ritchie and Thompson, incorporating several ideas from
colleagues. Eventually they decided to port the operating system to a PDP-11.
The original PDP-11 version of Unix was developed in assembly language. The
developers were considering to rewrite the system using the B language,
Thompson's simplified version of BCPL. However B's
inability to take advantage of some of the PDP-11's features, notably byte address-ability,
led to C.
The
development of C started in 1972 on the PDP-11 Unix system, and first appeared
in Version 2 Unix. The language was not
initially designed with portability in mind, but soon ran on different
platforms as well: a compiler for the Honeywell
6000 was written within the first year of C's history, while an IBM
System/370 port followed soon.
Also
in 1972, a large part of Unix was rewritten in C. By 1973, with the
addition of struct types, the C language had become powerful enough
that most of the Unix's kernel was now in C.
Unix
was one of the first operating system kernels implemented in a language other
than assembly. (Earlier instances include the Multics system
(written in PL/I),
and MCP (Master Control Program) for the Burroughs B5000 written in ALGOL in 1961.) Circa
1977, further changes to the language were made by Ritchie and Stephen C. Johnson to facilitate
portability of the Unix operating system. Johnson's Portable C Compiler served as the basis
for several implementations of C on new platforms.
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