page_title: History of the Berkeley Software Distribution
section_title: 4.3BSD
hierarchical_section_title: History of the Berkeley Software Distribution / 4.3BSD
caption_attribution_description: English: 4.3 BSD from the University of Wisconsin, running in the SIMH VAX-11/780 simulator with 16MB memory. The system describes itself as "4.3 BSD UNIX" and "4.3+NFS", and it dates to around January 1987.
context_page_description: The History of the Berkeley Software Distribution begins in the 1970s.
context_section_description: 4.3BSD was released in June 1986.  Its main changes were to improve the performance of many of the new contributions of 4.2BSD that had not been as heavily tuned as the 4.1BSD code. Prior to the release, BSD's implementation of TCP/IP had diverged considerably from BBN's official implementation. After several months of testing, DARPA determined that the 4.2BSD version was superior and would remain in 4.3BSD. (See also History of the Internet.)
  After 4.3BSD, it was determined that BSD would move away from the aging VAX platform. The Power 6/32 platform (codenamed "Tahoe") developed by Computer Consoles Inc. seemed promising at the time, but was abandoned by its developers shortly thereafter. Nonetheless, the 4.3BSD-Tahoe port (June 1988) proved valuable, as it led to a separation of machine-dependent and machine-independent code in BSD which would improve the system's future portability.
  Apart from portability, the CSRG worked on an implementation of the OSI network protocol stack, improvements to the kernel virtual memory system and (with Van Jacobson of LBL) new TCP/IP algorithms to accommodate the growth of the Internet.
  Until then, all versions of BSD incorporated proprietary AT&T Unix code and were, therefore, subject to an AT&T software license. Source code licenses had become very expensive and several outside parties had expressed interest in a separate release of the networking code, which had been developed entirely outside AT&T and would not be subject to the licensing requirement. This led to Networking Release 1 (Net/1), which was made available to non-licensees of AT&T code and was freely redistributable under the terms of the BSD license. It was released in June 1989.
  4.3BSD-Reno came in early 1990. It was an interim release during the early development of 4.4BSD, and its use was considered a "gamble", hence the naming after the gambling center of Reno, Nevada. This release was explicitly moving towards POSIX compliance, and, according to some, away from the BSD philosophy (as POSIX is very much based on System V, and Reno was quite bloated compared to previous releases). Among the new features were an NFS implementation from the University of Guelph and support for the HP 9000 range of computers, originating in the University of Utah's "HPBSD" port.
  In August 2006, InformationWeek magazine rated 4.3BSD as the "Greatest Software Ever Written". They commented: "BSD 4.3 represents the single biggest theoretical undergirder of the Internet."
caption: "4.3 BSD UNIX" from the University of Wisconsin circa 1987. System startup and login.
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