View source for 4.1 BSD

{{Infobox OS 
| image = 41bsd.png
| caption = Logging into a 4.1 BSD system
| name = 4.1 BSD
| creator = CSRG
| current version = 4.1 (1981)
| year introduced = 1981
| type = Multitasking, multiuser
| architecture = [[VAX]], theoretically portable
}}

This version addressed many of the performance shortcomings in [[4.0 BSD]] that were brought up in a VMS vs BSD paper.  Many of the changes are outlined in [[Bug fixes and changes in 4.1bsd]].  One of the big points of 4.1 is that it supported the [[VAX-11/750]], which became a workhorse favorite of the DoD, which in turn led to DARPA grants to the [[CSRG]] to continue developing BSD.  The 4.1 BSD kernel was systematically tuned up by Bill Joy until it could perform as well as [[VMS]] on several benchmarks.

The release would have been called 5BSD, but after objections from AT&T the name was changed; AT&T feared confusion with [[Unix SYSV|AT&T's UNIX System V]].

Other features included:

* job control 
* automatic kernel config 
* vfork() 

4.1 BSD, June 1981 4BSD was upgraded to include many performance improvements, support for a new VAX model and autoconfiguration.

Once DARPA was funding the development of BSD, it lead to 2 big improvements from 4.1 to 4.2: the adddition of [[TCP/IP]], and the new [[BSD Fast File System]]. These were beta-released in three intermediate versions: 4.1a included [[BBN]]'s preliminary [[TCP/IP]] implementation; 4.1b included the new FFS; and 4.1c was an interim release of what became [[4.2 BSD]], during the last few months of its development. 

Apparently 4.1a includes the BBN TCP/IP stack, but on a 750, it only can perform at 56kb on Ethernet, and maximizes the CPU to 100%, whereas Bill Joy's TCP/IP could get upwards of 700k/sec.

== Getting this to run ==

=== 4.1 ===
A tape image for 4.1 has surfaced on [[bitsavers]], named [http://bitsavers.trailing-edge.com/bits/UCB_CSRG/4.1_BSD_19810710.zip 4.1_BSD_19810710.zip]  The bootblock programs do not run under SIMH using the [[4.0 BSD]] strategy, however it is possible to swap tapes when restoring the root slice, and then restoring the tars.  Using this modified tape, I've created an installation guide [[Installing 4.1 BSD on SIMH]].

=== 4.1c ===
There is two tape images on bitsavers [http://bitsavers.trailing-edge.com/bits/UCB_CSRG/4.1C_BSD_1of2.zip 4.1C BSD 1 of 2], and [http://bitsavers.trailing-edge.com/bits/UCB_CSRG/4.1C_BSD_2of2.zip 4.1C BSD 2 of 2].  A much needed to revise guide is available [[Installing 4.1c BSD on SIMH]].

== Games ==
These are what is available on the 1981 tape:
<pre>
aardvark    banner      ching       lib         snake
adventure   bcd         cribbage    mille       snscore
advfiles    bogdict     fish        monop       trek
arithmetic  boggle      fortune     number      wump
backgammon  chess       hangman     quiz        zork
</pre>

== Documents ==

[[Bug fixes and changes in 4.1 BSD]]

== Post 4.1 releases ==


4.1a This was a test release including TCP/IP and the socket interface.  It saw a wide release, although it seems to have disappeared.

4.1b This was a test release, used only a Berkley and it includes the new Fast File System, using clustering for much improved performance, and contained the netw networking code.

4.1c 1982/1983 The thrid test release between 4.1BSD and 4.2BSD, it was distributed to about 100 sites and includes most 4.2 features except for the new signal facility.  There is a detailed paper [[UNIX* System V and 4.1C BSD]] written by John Chambers & John Quarterman, that details 4.1c BSD.

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