1BSD Released — The Berkeley Fork of UNIX Begins

In March 1977, the Computer Systems Research Group (CSRG) at the University of California, Berkeley shipped the First Berkeley Software Distribution (1BSD)—a tape of enhancements to AT&T Bell Labs' UNIX V6.

The editor in chief was Bill Joy, then a graduate student who would later co-found Sun Microsystems. The tape contained the ex editor (the ancestor of vi), a Pascal compiler, and a handful of utilities. Only about thirty copies were distributed.

From that small tape grew a half-century of UNIX lineage: SunOS, BSD/OS, FreeBSD, NetBSD, OpenBSD, and the Darwin kernel under macOS. The system software of the PlayStation 3, 4, and 5 and the streaming edge of Netflix all trace back to the BSD line.

Why UNIX Grew at Berkeley

In 1973, Ken Thompson visited his alma mater UC Berkeley with a tape of UNIX V4 for the PDP-11. Bound by antitrust constraints that kept it out of the computer business, AT&T was distributing UNIX to educational institutions at cost—source code included. The fact that universities received the source, not a commercial binary, was decisive.

At Berkeley, Bill Joy—then working on a Pascal implementation—seized on UNIX and began fixing every annoyance he hit: the ex editor, the csh shell, termcap, virtual-memory support. The cumulative pile of improvements eventually became substantial enough to redistribute.

What Was on the Tape

1BSD was not a complete operating system but a bundle of patches and additional utilities on top of UNIX V6:

• ex — a line-oriented editor with screen-mode capabilities, soon to evolve into vi (visual mode)
• A Pascal interpreter and compiler — Pascal was the standard teaching language of the era
• Shell improvements that would lead to csh in 2BSD
• termcap — a terminal-capability database that made portability across diverse terminals tractable

The tape sold for US$50 (cost of media and shipping). Sites that received it patched it further and sent tapes back. A bidirectional flow of source—what would later be called collaboration—was already happening, informally.

4BSD, TCP/IP, and Commercialisation

Key milestones that followed:

• 2BSD (1978) — Joy integrated csh and vi
• 3BSD (1979) — VAX support, virtual memory
• 4BSD (1980) — the DARPA-funded TCP/IP stack, soon to become the de facto reference implementation
• 4.2BSD (1983) — sockets, the embryonic NFS
• 4.3BSD (1986) — the basis for SunOS and Ultrix
• Net/2 (1991) — the first version stripped of AT&T-owned code, intended to be freely redistributable

The 4BSD TCP/IP implementation in particular is the bedrock of the modern internet. The protocol suite specified by Vint Cerf and others was first implemented at production quality in BSD UNIX—the moment when "plug a UNIX machine into Ethernet and you have an internet host" became real.

USL v. BSDi — A Rite of Passage for Open Source

In 1991, CSRG members commercialised their work as BSDi, which began selling a "free of AT&T code" BSD for US$1,000 a copy—against AT&T's own UNIX at tens of thousands of dollars. AT&T's subsidiary USL (UNIX System Laboratories) sued for copyright infringement and misappropriation of trade secrets.

The three-year lawsuit settled in 1994 with three lasting consequences:

• A small number of files of AT&T provenance had to be removed from BSD; the rest was confirmed as freely redistributable.
• The legal status of "redistributable source code" was tested and survived, but the cost of that test was high.
• During the years that BSD was legally frozen, the Linux kernel rose. The momentum advantage Linux gained in this window was, arguably, permanent.

The lawsuit left the open-source community with two lessons. First, the necessity of a culture that documents code provenance carefully and secures the right to redistribute by licence. Second, that resilience against corporate legal risk comes from multiple community-run derivatives running in parallel—the FreeBSD / NetBSD / OpenBSD model.

Where 1BSD Lives Today

Trace the modern descendants:

• macOS, iOS, iPadOS, watchOS, tvOS, visionOS — the Darwin kernel's userland and TCP/IP stack are BSD-derived
• PlayStation 3, 4, 5 — system software built on FreeBSD
• Netflix's streaming edge — runs FreeBSD for high-throughput TCP
• Junos (Juniper Networks router OS) — FreeBSD-based
• WhatsApp's servers — once carried two billion users on FreeBSD

A small tape distributed in thirty copies in 1977 still underwrites the world's communications, media, and gaming infrastructure. As the first practical demonstration of "sharing source code as a way of building software", 1BSD precedes GNU, Linux, Apache, and Git in the genealogy of open source.