Research Unix

AT&T licensed Version 5 to educational institutions, and Version 6 also to commercial sites. Schools paid $200 and others $20,000, discouraging most commercial use, but Version 6 was the most widely used version into the 1980s. Research Unix versions are often referred to by the edition of the manual that describes them, because early versions and the last few were never officially released outside of Bell Labs, and grew organically. So, the first Research Unix would be the First Edition, and the last the Tenth Edition. Another common way of referring to them is as "Version x Unix" or "Vx Unix", where x is the manual edition. All modern editions of Unix—excepting Unix-like implementations such as Coherent, Minix, and Linux—derive from the 7th Edition. Starting with the 8th Edition, versions of Research Unix had a close relationship to BSD. This began by using 4.1cBSD as the basis for the 8th Edition. In a Usenet post from 2000, Dennis Ritchie described these later versions of Research Unix as being closer to BSD than they were to UNIX System V, which also included some BSD code: == Versions ==

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. Later, in January 2002, Caldera International (later to become SCO Group and made defunct) relicensed (but has not made available) several versions under the four-clause BSD license, up to and including Version 7 Unix (UNIX/32V). 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. SCO Group, Inc. was previously called Caldera International. As a result of the SCO Group, Inc. v. Novell, Inc. case, Novell, Inc. was found not to have transferred the copyrights of UNIX to SCO Group, Inc. Concerns have been raised regarding the validity of the Caldera license. ==The Unix Heritage Society==

The Unix Heritage Society was founded by Warren Toomey. First edition Unix was restored to a usable state by a restoration team from the Unix Heritage Society in 2008. The restoration process started with paper listings of the source code which were in PDP-11 assembly language. == Legacy ==

In 2002, Caldera International released Unix V1, V2, V3, V4, V5, V6, V7 on PDP-11 and Unix 32V on VAX as FOSS under a permissive BSD-like software license. In 2017, The Unix Heritage Society and Alcatel-Lucent USA Inc., on behalf of itself and Nokia Bell Laboratories, released V8, V9, and V10 under the condition that only non-commercial use was allowed, and that they would not assert copyright claims against such use. == See also ==