Version 6 Unix
Encyclopedia
Sixth Edition Unix, also called Version 6 Unix or just V6, was the first version of the Unix
operating system
to see wide release outside Bell Labs
. It was released in May 1975 and, like its direct predecessor, targeted the DEC
PDP-11
family of minicomputer
s. It was superseded by Version 7 Unix
in 1978/1979.
Bell Labs developed several variants of V6, including the stripped-down MINI-UNIX for low-end PDP-11 models, LSI-UNIX or LSX for the LSI-11, and the real-time operating system
UNIX/RT, which merged V6 Unix and the earlier MERT hypervisor.http://portal.acm.org/citation.cfm?id=806519
An enhanced V6 was the basis of the first ever commercially sold Unix version, INTERACTIVE
's IS/1. Bell's own PWB/UNIX
1.0 was also based on V6, where earlier (unreleased) versions were based on V4 and V5. Whitesmiths
produced and marketed a (binary-compatible) V6 clone under the name Idris
.
Since source code
was available and the license was not explicit enough to forbid it, V6 was taken up as a teaching tool, notably by the University of California, Berkeley
and the University of New South Wales
(UNSW). Berkeley distributed a set of add-on program called the First Berkeley Software Distribution
or 1BSD, which later became a full-fledged operating system. UNSW professor John Lions
' famous Commentary on UNIX 6th Edition
was an edited selection of the main parts of the kernel as implemented for a Digital PDP-11/40, and was the main source of kernel documentation for many early Unix developers. Due to license restrictions on later Unix versions, the book was mainly distributed by samizdat
photo-copying. Also in New South Wales
, a group at Wollongong University completed a port to the Interdata 7/32 in 1977 called Wollongong Interdata UNIX, Level 6, thus proving the portability of Unix and its new systems programming language C
. A Bell Labs port to the Interdata 8/32 was not released. The University of Sydney
released the Australian Unix Share Accounting Method (AUSAM) in November 1979, a V6 variant with improved security and process accounting.
In the Eastern Bloc
, clones of V6 Unix appeared for local-built PDP-11 clones (MNOS
, later augmented for partial compatibility with BSD Unix) and for the Elektronika BK
personal computer (BKUNIX
, based on LSX).
The code for the original V6 Unix has been made available under a BSD License under agreement from the SCO Group
; see Ancient UNIX Systems
.
in 2002 through 2006, and subsequently replaced by an x86 clone called xv6
.
Unix
Unix is a multitasking, multi-user computer operating system originally developed in 1969 by a group of AT&T employees at Bell Labs, including Ken Thompson, Dennis Ritchie, Brian Kernighan, Douglas McIlroy, and Joe Ossanna...
operating system
Operating system
An operating system is a set of programs that manage computer hardware resources and provide common services for application software. The operating system is the most important type of system software in a computer system...
to see wide release outside Bell Labs
Bell Labs
Bell Laboratories is the research and development subsidiary of the French-owned Alcatel-Lucent and previously of the American Telephone & Telegraph Company , half-owned through its Western Electric manufacturing subsidiary.Bell Laboratories operates its...
. It was released in May 1975 and, like its direct predecessor, targeted the DEC
Digital Equipment Corporation
Digital Equipment Corporation was a major American company in the computer industry and a leading vendor of computer systems, software and peripherals from the 1960s to the 1990s...
PDP-11
PDP-11
The PDP-11 was a series of 16-bit minicomputers sold by Digital Equipment Corporation from 1970 into the 1990s, one of a succession of products in the PDP series. The PDP-11 replaced the PDP-8 in many real-time applications, although both product lines lived in parallel for more than 10 years...
family of minicomputer
Minicomputer
A minicomputer is a class of multi-user computers that lies in the middle range of the computing spectrum, in between the largest multi-user systems and the smallest single-user systems...
s. It was superseded by Version 7 Unix
Version 7 Unix
Seventh Edition Unix, also called Version 7 Unix, Version 7 or just V7, was an important early release of the Unix operating system. V7, released in 1979, was the last Bell Laboratories release to see widespread distribution before the commercialization of Unix by AT&T in the early 1980s...
in 1978/1979.
Bell Labs developed several variants of V6, including the stripped-down MINI-UNIX for low-end PDP-11 models, LSI-UNIX or LSX for the LSI-11, and the real-time operating system
Real-time operating system
A real-time operating system is an operating system intended to serve real-time application requests.A key characteristic of a RTOS is the level of its consistency concerning the amount of time it takes to accept and complete an application's task; the variability is jitter...
UNIX/RT, which merged V6 Unix and the earlier MERT hypervisor.http://portal.acm.org/citation.cfm?id=806519
An enhanced V6 was the basis of the first ever commercially sold Unix version, INTERACTIVE
INTERACTIVE Systems Corporation
INTERACTIVE Systems Corporation was a US-based software company and the first vendor of the Unix operating system outside AT&T, operating from Santa Monica, CA....
's IS/1. Bell's own PWB/UNIX
PWB/UNIX
The Programmer's Workbench was an early version of the Unix operating system created in the Bell Labs Computer Science Research Group of AT&T....
1.0 was also based on V6, where earlier (unreleased) versions were based on V4 and V5. Whitesmiths
Whitesmiths
Whitesmiths Ltd. was a software company based in Westford, Massachusetts. It sold a Unix-like operating system called Idris, as well as the first commercial C compiler...
produced and marketed a (binary-compatible) V6 clone under the name Idris
Idris (operating system)
Idris is a multi-tasking, Unix-like, multi-user, real-time operating system released by Whitesmiths, of Westford, Massachusetts. The product was commercially available from 1979 through 1988.-Background:...
.
Since source code
Source code
In computer science, source code is text written using the format and syntax of the programming language that it is being written in. Such a language is specially designed to facilitate the work of computer programmers, who specify the actions to be performed by a computer mostly by writing source...
was available and the license was not explicit enough to forbid it, V6 was taken up as a teaching tool, notably by the University of California, Berkeley
University of California, Berkeley
The University of California, Berkeley , is a teaching and research university established in 1868 and located in Berkeley, California, USA...
and the University of New South Wales
University of New South Wales
The University of New South Wales , is a research-focused university based in Kensington, a suburb in Sydney, New South Wales, Australia...
(UNSW). Berkeley distributed a set of add-on program called the First Berkeley Software Distribution
Berkeley Software Distribution
Berkeley Software Distribution is a Unix operating system derivative developed and distributed by the Computer Systems Research Group of the University of California, Berkeley, from 1977 to 1995...
or 1BSD, which later became a full-fledged operating system. UNSW professor John Lions
John Lions
John Lions was an Australian computer scientist. He is best known as the author of Lions' Commentary on UNIX 6th Edition, with Source Code, commonly known as the Lions Book.-Early life:...
' famous Commentary on UNIX 6th Edition
Lions' Commentary on UNIX 6th Edition, with Source Code
Lions' Commentary on UNIX 6th Edition, with Source Code by John Lions contains the complete source code of the 6th Edition Unix kernel plus a commentary. It is commonly referred to as the Lions book...
was an edited selection of the main parts of the kernel as implemented for a Digital PDP-11/40, and was the main source of kernel documentation for many early Unix developers. Due to license restrictions on later Unix versions, the book was mainly distributed by samizdat
Samizdat
Samizdat was a key form of dissident activity across the Soviet bloc in which individuals reproduced censored publications by hand and passed the documents from reader to reader...
photo-copying. Also in New South Wales
New South Wales
New South Wales is a state of :Australia, located in the east of the country. It is bordered by Queensland, Victoria and South Australia to the north, south and west respectively. To the east, the state is bordered by the Tasman Sea, which forms part of the Pacific Ocean. New South Wales...
, a group at Wollongong University completed a port to the Interdata 7/32 in 1977 called Wollongong Interdata UNIX, Level 6, thus proving the portability of Unix and its new systems programming language C
C (programming language)
C is a general-purpose computer programming language developed between 1969 and 1973 by Dennis Ritchie at the Bell Telephone Laboratories for use with the Unix operating system....
. A Bell Labs port to the Interdata 8/32 was not released. The University of Sydney
University of Sydney
The University of Sydney is a public university located in Sydney, New South Wales. The main campus spreads across the suburbs of Camperdown and Darlington on the southwestern outskirts of the Sydney CBD. Founded in 1850, it is the oldest university in Australia and Oceania...
released the Australian Unix Share Accounting Method (AUSAM) in November 1979, a V6 variant with improved security and process accounting.
In the Eastern Bloc
Eastern bloc
The term Eastern Bloc or Communist Bloc refers to the former communist states of Eastern and Central Europe, generally the Soviet Union and the countries of the Warsaw Pact...
, clones of V6 Unix appeared for local-built PDP-11 clones (MNOS
MNOS
MNOS was a Unix-like operating system developed in the Soviet Union. It was derived from Unix Version 6 and consequently heavily modified to incorporate many features of BSD Unix...
, later augmented for partial compatibility with BSD Unix) and for the Elektronika BK
Elektronika BK
The Elektronika BK was a series of 16-bit PDP-11-compatible Soviet home computers developed by NPO Scientific Center, the leading Soviet microcomputer design team at the time. It was also responsible for the more powerful UKNC and DVK micros...
personal computer (BKUNIX
BKUNIX
BKUNIX is an operating system for the Soviet Elektronika BK personal computer. It is based on LSX kernel and licensed under the GNU General Public License. It is developed by Sergey Vakulenko and Leonid Broukhis. BK-0010 and BK-0011M require different compilations of the kernel, but other parts...
, based on LSX).
The code for the original V6 Unix has been made available under a BSD License under agreement from the SCO Group
SCO Group
TSG Group, Inc. is a software company formerly called The SCO Group, Caldera Systems, and Caldera International. After acquiring the Santa Cruz Operation's Server Software and Services divisions, as well as UnixWare and OpenServer technologies, the company changed its focus to UNIX...
; see Ancient UNIX Systems
Ancient UNIX Systems
Ancient UNIX is a term coined by Santa Cruz Operation, to describe early releases of the Unix code base released prior to Unix System III, particularly the Research Unix releases prior to and including Version 7 .After the publication of the Lions' book, work was undertaken to release the earlier...
.
xv6
V6 was used for teaching at MITMassachusetts Institute of Technology
The Massachusetts Institute of Technology is a private research university located in Cambridge, Massachusetts. MIT has five schools and one college, containing a total of 32 academic departments, with a strong emphasis on scientific and technological education and research.Founded in 1861 in...
in 2002 through 2006, and subsequently replaced by an x86 clone called xv6
Xv6
xv6 is a modern reimplementation of Sixth Edition Unix in ANSI C for multiprocessor x86 systems. It is used for pedagogical purposes in MIT's Operating Systems Engineering course. Unlike Linux or BSD, xv6 is simple enough to cover in a semester, yet still contains the important concepts and...
.
External links
- V6 source code
- Wollongong Interdata UNIX source code
- Unix V6 Manuals - Web interface to the V6 manual pages.
- Unix V6 documents, eg. C Reference, and man pages
- The First Unix Port; Richard Miller's account of porting Unix to the Interdata 7/32
- Unix V5, V6 and V7 for PDP-11 installed in SIMH emulator on MS Windows
- Unix v6 for PDP-11 online emulator