Computer Systems Research Group

The Computer Systems Research Group (CSRG) was a research group at the University of California, Berkeley that was dedicated to enhancing AT&T Unix operating system and funded by Defense Advanced Research Projects Agency.

Professor Bob Fabry of University of California, Berkeley acquired a UNIX source license from AT&T in 1974. Berkeley started to modify UNIX and distributed their version of UNIX as BSD (Berkeley Software Distribution). In April 1980 Professor Fabry signed a contract with the Defense Advanced Research Projects Agency to develop UNIX even further to accommodate the specific requirements of the ARPAnet. With funding from DARPA, Fabry created the Computer Systems Research Group. The BSD Sockets API and Berkeley Fast File System are some of the most noteworthy innovations of the group. The sockets interface solved the problem of supporting multiple protocols (e.g. XNS and TCP/IP), and also extended UNIX's "everything is a file" notion to these network protocols, while the fast file system increased the block allocation size from 512 bytes to 4096 bytes (or larger), improving disk transfer performance, while also allowing "micro-blocks" as small as 128 bytes, which improved disk utilization. Another noteworthy contribution was the job control signals, which allowed a user to suspend a job with a key-press (control-Z), and then continue running the job in the background under the C shell.

Noteworthy versions of BSD were 3.0 BSD (the first version of BSD to support virtual memory), 4.0 BSD (which included the job-control CTRL-Z functionality, to suspend and restart a running job), a special 4.15 (interim) BSD version which had been released using BBN's TCP/IP, and 4.2 BSD (which included a full Berkeley sockets TCP/IP stack, the fast file system, and NFS support.)

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