Columbus UNIX was, according to Marc Rochkind

Marc Rochkind

Marc J. Rochkind invented the Source Code Control System while working at Bell Labs, as well as wrote , and founded .-Source Code Control System:The Source Code Control System was the first modern revision control system. SCCS was developed by Rochkind in 1972 at Bell Labs...

, a variant of the UNIX

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...

 internal to 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 developed at the Columbus

Columbus, Ohio

Columbus is the capital of and the largest city in the U.S. state of Ohio. The broader metropolitan area encompasses several counties and is the third largest in Ohio behind those of Cleveland and Cincinnati. Columbus is the third largest city in the American Midwest, and the fifteenth largest city...

, Ohio

Ohio

Ohio is a Midwestern state in the United States. The 34th largest state by area in the U.S.,it is the 7th‑most populous with over 11.5 million residents, containing several major American cities and seven metropolitan areas with populations of 500,000 or more.The state's capital is Columbus...

 branch and was little-known outside the company. CB UNIX was developed to address deficiencies inherent in Research Unix

Research Unix

Research Unix is a term used to refer to 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 Science Research Center ....

, notably the lack of interprocess communication and file locking

File locking

File locking is a mechanism that restricts access to a computer file by allowing only one user or process access at any specific time. Systems implement locking to prevent the classic interceding update scenario ....

, considered essential for a database management system

Database management system

A database management system is a software package with computer programs that control the creation, maintenance, and use of a database. It allows organizations to conveniently develop databases for various applications by database administrators and other specialists. A database is an integrated...

. Several Bell System

Bell System

The Bell System was the American Bell Telephone Company and then, subsequently, AT&T led system which provided telephone services to much of the United States and Canada from 1877 to 1984, at various times as a monopoly. In 1984, the company was broken up into separate companies, by a U.S...

 operation support system products were based on CB UNIX such as Switching Control Center System

Switching Control Center System

The Switching Control Center System was an Operations Support System developed by Bell Laboratories and deployed during the early 1970s. This computer system was first based on the PDP-11 product line from Digital Equipment Corporation and used the CB Unix operating system and custom application...

. The primary innovations were power-fail restart, line disciplines, terminal types, and IPC features similar to System V's messages and shared memory

Shared memory

In computing, shared memory is memory that may be simultaneously accessed by multiple programs with an intent to provide communication among them or avoid redundant copies. Depending on context, programs may run on a single processor or on multiple separate processors...

.