Release Date: Edition 2.1: November, 1979; Release 3: February 9, 1980; Edition 2.3: May, 1981
Released By: CB-UNIX Support Group
Source Code: SourceCode contains PDF scans of a paper source printout of the “CB UNIX Release 3” kernel dated February 9, 1980
Documentation: CB_Unix/man contains PDF scans of the CB-UNIX Programmer's Manual Edition 2.3, issued May, 1981. CB_Unix_Manuals.jpg is an image of the covers of a two-volume CB-UNIX Programmer's Manual set.

CB-UNIX was a branch of UNIX within the Bell System maintained primarily by the CB-UNIX Support Group in Columbus, Ohio. Among its many applications were real-time processing and the Switching Control Center System. Many features from CB-UNIX would eventually appear in commercial releases, such as the init system used in System V.

The above version numbers may be a bit confusing, but they are directly from available documentation. The manual linked is subtitled “Edition 2.3” on the front page, and many pages remain from a past “Edition 2.1” manual as printed in their footers. However, in the version.h file of the scanned source code, there are two CB-UNIX version definitions, UV_CBR2 and UV_CBR3. UV_CBR2 has a comment of “CB UNIX Release 2 -- version 6 filesystem”. UV_CBR3 has no comment but presumably would indicate a “Release 3” of this same nomenclature. UV_CBR3 is then defined as the current format for executables in the same header. Whether this means that the manual editions had more to do with manual compilation revisions than tracking a versioning scheme in the system is not currently known.

Of the streams of UNIX documentation, the CB-UNIX manual shares the most in common with the Programmer's Workbench lineage of manuals. For instance, the numbering and naming scheme of the sections bear similarities and much of the particular variations in language coincide.