UNIX Third Edition

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Unix V3
Type: Multi-tasking, multi-user
Creator: AT&T/Western Electric
Architecture: PDP-11
Previous Version: V2
Current Version: V3
Next Version: V4
Date Released: February, 1973


UNIX Third Edition (often referred to as UNIX V3 or V3 UNIX - 'Unix' was still normally given in all capital letters at this point in time) was a significant early version of UNIX. It was the version in which pipes appeared, and the last version in which the kernel was written in assembly language.

It still ran on the PDP-11/20 model of the PDP-11, as well as the PDP-11/45 (apparently). The file system apparently identical to the one in UNIX Second Edition; i.e. almost identical to the V6 one: the only major differences being that i) the free blocks are stored as a bit array, rather than a list, and ii) device 'special files' are indicated by inode numbers below 41. (not via a flag in the 'mode' word in the inode, as later).

A complete copy of Third Edition does not seem to be extant. TUHS has a copy of the 'UNIX Programmer's Manual Third Edition', and the source code for an early version of the first C compiler (C was just being defined at the point in time, although it first appeared in UNIX Second Edition).

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