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Old 26th November 2013
muflon muflon is offline
Fdisk Soldier
Join Date: Jul 2013
Location: Poland
Posts: 56

Every program for the original PDP-7 Unix system was written in assembly language, and bare assembly language it was - for example, there were no macros.
Moreover, there was no loader or link-editor, so every program had to be complete in itself.

The first interesting language, as is mentioned by Dennis Ritchie, was a version of McClure's TMG that McIlroy implemented to PDP. [R. M. McClure, 'TMG--A Syntax-Directed Compiler,' Proc 20th ACM National Conf. 1968, pp. 262-74]

After TMG became available, Thomson decided that Unix could not pretend to offer a real computing service without Fortran, so he sat down to write a Fortran in TMG.

Instead, after a week of hard work, Thompson produced a definition of and a compiler for the new language. B language. There is a good article about it, that was written by S. C. Johnson and B. W. Kernighan, 'The Programming Language B,' Comp. Sci. Tech. Rep. #8, Bell Laboratories, Murray Hill NJ 1973.

B was much influenced by the BCPL language [ M. Richards, 'BCPL: A Tool for Compiler Writing and System Programming,' Proc. AFIPS SJCC 34 1969, pp. 557-66 ], other influences were Thompson's taste for 'spartan syntax', and the very small space into which the compiler had to fit.

The compiler produced simple interpretive code; although it and the programs it produced were rather slow, it made life much more pleasant.

The next step was made in 1971 when work began on what was to become the C language.
The story of the language developments from BCPL through B to C is told in D.M. Ritchie, S.C. Johnson, and M. E. Lesk, 'The C Programming Language,', Bell Sys. Tech. J., 57 No. 6 (July-August 1978), pp. 1991-2019

So I don't know is there any need to understand the root's of today's OS.
But we could talk. Anyway.
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