Sixth Edition Unix, also called Version 6 Unix or just V6 is a version of the
Unix
Unix (, ; trademarked as UNIX) is a family of multitasking, multi-user computer operating systems that derive from the original AT&T Unix, whose development started in 1969 at the Bell Labs research center by Ken Thompson, Dennis Ritchie, a ...
operating system
An operating system (OS) is system software that manages computer hardware and software resources, and provides common daemon (computing), services for computer programs.
Time-sharing operating systems scheduler (computing), schedule tasks for ...
first released in May 1975 and the first version of the
Unix
Unix (, ; trademarked as UNIX) is a family of multitasking, multi-user computer operating systems that derive from the original AT&T Unix, whose development started in 1969 at the Bell Labs research center by Ken Thompson, Dennis Ritchie, a ...
operating system
An operating system (OS) is system software that manages computer hardware and software resources, and provides common daemon (computing), services for computer programs.
Time-sharing operating systems scheduler (computing), schedule tasks for ...
to see wide release outside
Bell Labs
Nokia Bell Labs, commonly referred to as ''Bell Labs'', is an American industrial research and development company owned by Finnish technology company Nokia. With headquarters located in Murray Hill, New Jersey, Murray Hill, New Jersey, the compa ...
. Like its direct predecessor, the sixth edition targeted the
DEC PDP-11
The PDP–11 is a series of 16-bit minicomputers originally sold by Digital Equipment Corporation (DEC) from 1970 into the late 1990s, one of a set of products in the Programmed Data Processor (PDP) series. In total, around 600,000 PDP-11s of a ...
family of
minicomputer
A minicomputer, or colloquially mini, is a type of general-purpose computer mostly developed from the mid-1960s, built significantly smaller and sold at a much lower price than mainframe computers . By 21st century-standards however, a mini is ...
s. It was superseded by
Version 7 Unix
Version 7 Unix, also called Seventh Edition 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 commerc ...
in 1978/1979, although V6 systems remained in regular operation until at least 1985.
AT&T Corporation
AT&T Corporation, an abbreviation for its former name, the American Telephone and Telegraph Company, was an American telecommunications company that provided voice, video, data, and Internet telecommunications and professional services to busi ...
licensed
Version 5 Unix
Research Unix refers to the early versions of the Unix operating system for DEC PDP-7, PDP-11, VAX and Interdata 7/32 and 8/32 computers, developed in the Bell Labs Computing Sciences Research Center (CSRC). The term ''Research Unix'' first appe ...
to educational institutions only, but licensed Version 6 also to commercial users for $20,000, and it remained the most widely used version into the 1980s.
An enhanced V6 was the basis of the first ever commercially sold Unix version,
INTERACTIVE
Across the many fields concerned with interactivity, including information science, computer science, human-computer interaction, communication, and industrial design, there is little agreement over the meaning of the term "interactivity", but mo ...
's IS/1. Bell's own
PWB/UNIX
The Programmer's Workbench (PWB/UNIX) was an early, now discontinued, version of the Unix operating system that had been created in the Bell Labs Computer Science Research Group of AT&T. Its stated goal was to provide a time-sharing working envi ...
1.0 was also based on V6, where earlier (unreleased) versions were based on V4 and V5.
Whitesmiths
Whitesmiths Ltd. was a software company founded in New York City by P. J. Plauger, Mark Krieger and Gabriel Pham, and last located in Westford, Massachusetts. It sold a Unix-like operating system called Idris, as well as the first commercial C ...
produced and marketed a (binary-compatible) V6 clone under the name
Idris
Idris may refer to:
People
* Idris (name), a list of people and fictional characters with the given name or surname
* Idris (prophet), Islamic prophet in the Qur'an, traditionally identified with Enoch, an ancestor of Noah in the Bible
* Idris ...
.
Source code

V6 Unix was released as a distribution including the full
source code
In computing, source code, or simply code or source, is a plain text computer program written in a programming language. A programmer writes the human readable source code to control the behavior of a computer.
Since a computer, at base, only ...
. 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
The University of California, Berkeley (UC Berkeley, Berkeley, Cal, or California), is a Public university, public Land-grant university, land-grant research university in Berkeley, California, United States. Founded in 1868 and named after t ...
,
Johns Hopkins University
The Johns Hopkins University (often abbreviated as Johns Hopkins, Hopkins, or JHU) is a private university, private research university in Baltimore, Maryland, United States. Founded in 1876 based on the European research institution model, J ...
and the
University of New South Wales
The University of New South Wales (UNSW) is a public research university based in Sydney, New South Wales, Australia. It was established in 1949.
The university comprises seven faculties, through which it offers bachelor's, master's and docto ...
(UNSW).
UC Berkeley distributed a set of add-on programs called the
First Berkeley Software Distribution or 1BSD, which later became a complete operating system distribution.
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
Samizdat (, , ) was a form of dissident activity across the Eastern Bloc in which individuals reproduced censored and underground makeshift publications, often by hand, and passed the documents from reader to reader. The practice of manual rep ...
'' photo-copying.
The source code for the original V6 Unix was later made available as
free software
Free software, libre software, libreware sometimes known as freedom-respecting software is computer software distributed open-source license, under terms that allow users to run the software for any purpose as well as to study, change, distribut ...
under a
BSD License
BSD licenses are a family of permissive free software licenses, imposing minimal restrictions on the use and distribution of covered software. This is in contrast to copyleft licenses, which have share-alike requirements. The original BSD lic ...
from the
SCO Group
The SCO Group (often referred to SCO and later called The TSG Group) was an American software company in existence from 2002 to 2012 that became known for owning Unix operating system assets that had belonged to the Santa Cruz Operation (the or ...
.
Portability
Interdata 7/32
In 1977, Richard Miller and Ross Nealon, working under the supervision of professor Juris Reinfelds at
Wollongong University, completed a port of V6 Unix to the
Interdata 7/32, thus proving the portability of Unix and its new systems programming language
C in practice. Their "Wollongong Interdata UNIX, Level 6" also included utilities developed at Wollongong, and later releases had features of V7, notably its
C compiler
In computing, a compiler is a computer program that Translator (computing), translates computer code written in one programming language (the ''source'' language) into another language (the ''target'' language). The name "compiler" is primaril ...
. Wollongong Unix was the first ever port to a platform other than the PDP series of computers, proving that portable operating systems were indeed feasible, and that C was the language in which to write them. In 1980, this version was licensed to
The Wollongong Group in Palo Alto that published it as Edition 7.
Interdata 8/32
Around the same time, a Bell Labs port to the Interdata 8/32 was completed, but not externally released. The goal of this port was to improve the portability of Unix more generally, as well to produce a portable version of the C compiler.
The resulting
Portable C Compiler
The Portable C Compiler (also known as pcc or sometimes pccm - portable C compiler machine) is an early compiler for the C programming language written by Stephen C. Johnson of Bell Labs in the mid-1970s, based in part on ideas proposed by Alan ...
(PCC) was distributed with V7 and many later versions of Unix, and was used to produce the
UNIX/32V
UNIX/32V is an early version of the Unix operating system from Bell Laboratories, released in June 1979. 32V was a direct port of the Seventh Edition Unix to the DEC VAX architecture.
Overview
Before 32V, Unix had primarily run on DEC PDP-11 ...
port to the
VAX
VAX (an acronym for virtual address extension) is a series of computers featuring a 32-bit instruction set architecture (ISA) and virtual memory that was developed and sold by Digital Equipment Corporation (DEC) in the late 20th century. The V ...
.
IBM VM/370
A third Unix portability project was completed at
Princeton, NJ
The Municipality of Princeton is a Borough (New Jersey), borough in Mercer County, New Jersey, United States. It was established on January 1, 2013, through the consolidation of the Borough of Princeton, New Jersey, Borough of Princeton and Pri ...
in 1976–1977, where the Unix kernel was adapted to run as a guest operating on IBM's
VM/370
VM (often: VM/CMS) is a family of IBM virtual machine operating systems used on IBM mainframes System/370, System/390, zSeries, System z and compatible systems, including the Hercules emulator for personal computers.
Design
The heart of t ...
virtualization environment.
This version became the nucleus of Amdahl's first internal UNIX offering. (see
Amdahl UTS)
Variants and extensions
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
The PDP–11 is a series of 16-bit minicomputers originally sold by Digital Equipment Corporation (DEC) from 1970 into the late 1990s, one of a set of products in the Programmed Data Processor (PDP) series. In total, around 600,000 PDP-11s of al ...
, and the
real-time operating system
A real-time operating system (RTOS) is an operating system (OS) for real-time computing applications that processes data and events that have critically defined time constraints. A RTOS is distinct from a time-sharing operating system, such as Unix ...
UNIX/RT, which merged V6 Unix and the earlier
MERT hypervisor.
After AT&T decided the distribution by Bell Labs of a number of pre-V7 bug fixes would constitute support (disallowed by an antitrust settlement) a tape with the patchset was slipped to Lou Katz of
USENIX
USENIX is an American 501(c)(3) nonprofit membership organization based in Berkeley, California and founded in 1975 that supports advanced computing systems, operating system (OS), and computer networking research. It organizes several confe ...
, who distributed them.
The
University of Sydney
The University of Sydney (USYD) is a public university, public research university in Sydney, Australia. Founded in 1850, it is the oldest university in both Australia and Oceania. One of Australia's six sandstone universities, it was one of the ...
released the Australian Unix Share Accounting Method (AUSAM) in January 1978, a V6 variant with improved security and process accounting, in addition to the fifty fixes that leaked out of Bell Labs. There were several subsequent releases.
Interactive Systems Corporation
Interactive Systems Corporation (styled INTERACTIVE Systems Corporation, abbreviated ISC) was a US-based software company and the first vendor of the Unix operating system outside AT&T, operating from Santa Monica, California. It was founded in 1 ...
released an enhanced
PDP-11
The PDP–11 is a series of 16-bit minicomputers originally sold by Digital Equipment Corporation (DEC) from 1970 into the late 1990s, one of a set of products in the Programmed Data Processor (PDP) series. In total, around 600,000 PDP-11s of a ...
version for office automation called
IS/1.
In the
Eastern Bloc
The Eastern Bloc, also known as the Communist Bloc (Combloc), the Socialist Bloc, the Workers Bloc, and the Soviet Bloc, was an unofficial coalition of communist states of Central and Eastern Europe, Asia, Africa, and Latin America that were a ...
, 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
The Electronika BK is a series of 16-bit PDP-11-compatible home computers developed under the Electronika brand by NPO Scientific Center, then the leading microcomputer design team in the Soviet Union. It is also the predecessor of the more power ...
personal computer (
BKUNIX, based on LSX).
V6 was used for teaching at
MIT
The Massachusetts Institute of Technology (MIT) is a private research university in Cambridge, Massachusetts, United States. Established in 1861, MIT has played a significant role in the development of many areas of modern technology and sc ...
in 2002 through 2006, and subsequently replaced by a simpler clone called
xv6.
See also
*
Ancient UNIX
Ancient history is a time period from the beginning of writing and recorded human history through late antiquity. The span of recorded history is roughly 5,000 years, beginning with the development of Sumerian cuneiform script. Ancient hi ...
*
References
External links
V6 source codeWollongong Interdata UNIX source codeUnix V6 Manuals– Web interface to the V6 manual pages.
Unix V6 documents, e.g. C Reference, and man pagesThe First Unix Port Richard Miller's account of porting Unix to the Interdata 7/32
Unix v6 for PDP-11 online emulator
{{Unix-like
Bell Labs Unices
Discontinued operating systems
Unix history
Unix variants
Free software operating systems
1975 software