Ancient UNIX

Version 5 Unix for the PDP-11, running on SIMH
Version 6 Unix for the PDP-11, running in SIMH
Version 7 Unix for the PDP-11, running in SIMH

Ancient UNIX is any early release of the Unix code base prior to Unix System III, particularly the Research Unix releases prior to and including Version 7 (the base for UNIX/32V as well as later developments of AT&T Unix).

After the publication of the Lions' book, work was undertaken to release earlier versions of the codebase. SCO first released the code under a limited educational license.[citation needed]

Later, in January 2002, Caldera International (now SCO Group) relicensed (but has not made available) several versions under the four-clause BSD license, namely:[1][2]

As of 2022, there has been no widespread use of the code, but it can be used on emulator systems, and Version 5 Unix runs on the Nintendo Game Boy Advance using the SIMH PDP-11 emulator.[3] Version 6 Unix provides the basis for the MIT xv6 teaching system, which is an update of that version to ANSI C and the x86 or RISC-V platform.

The BSD vi text editor is based on code from the ed line editor in those early Unixes. Therefore, "traditional" vi could not be distributed freely, and various work-alikes (such as nvi) were created. Now that the original code is no longer encumbered, the "traditional" vi has been adapted for modern Unix-like operating systems.[4]

SCO Group, Inc. was previously called Caldera International. As a result of the SCO Group, Inc. v. Novell, Inc. case, Novell, Inc. was found to not have transferred the copyrights of UNIX to SCO Group, Inc.[5] Concerns have been raised regarding the validity of the Caldera license.[6][7]

  1. ^ Johnson II, Dion L. (2002-01-24). "Liberal license for ancient UNIX sources".
  2. ^ Broderick, Bill (January 23, 2002). "Dear Unix enthusiasts" (PDF). Caldera International. Archived from the original (PDF) on February 19, 2009.
  3. ^ Singh, Amit (August 2004). "UNIX® on the Game Boy Advance". Archived from the original on 2006-08-31. Retrieved 2009-10-22.
  4. ^ "The Traditional Vi".
  5. ^ "10th Circuit Court of Appeals Decision" (PDF).
  6. ^ Warren Toomey. "The Push to Get Free Unix Licenses".
  7. ^ "Why BSD/OS is the best candidate for being the only tested legally open UNIX".