Chapter 2 LINUX History Unix History The number
Chapter 2 LINUX History
Unix History “The number of UNIX installations has grown to 10, with more expected” - UNIX Programmer’s Manual, 1972
UNIX as an Operating System • • • Run-time environment System services Utilities Libraries User programs
Systems Supported by UNIX • • • Multiprocessor Computers High Performance Computers Work Stations Personal Computers Embedded Processors In short, all kinds of computers
UNIX Variants • • System V Release 4 (SVR 4) by Novell, Inc. University of California Berkeley UNIX (4. x. BSD) SUN OS Solaris Digital UNIX HP-UX, XENIX, AIX, VENIX Clones, such as Linux
UNIX Variants Features Commonalities: • A core set of interfaces • A core set of features • Applications Differences: • Internal Implementation • Interface Semantics • Some features
Historic Milestones • Multics Project at Bell Labs (1966 – 1969) • Thompson and Ritchie’s first UNIX on a PDP-7: a mechanism to support program development (1969) • Thompson’s B language (interpreted) used as a language for development (1970) • Ritchie evolved B into C, a compiled language (1971) • UNIX rewritten in C (1973)
Historic Milestones (cont. ) • AT&T provides UNIX free to Universities (starting with Berkeley in 1973) • UNIX version 7 released as the first portable version (1979) • Users improved performance of version 7 and AT&T incorporated user changes in later versions
Historic Milestones (cont. ) • First 32 bit version developed for the VAX-11 (1978) and later evolved into 3 BSD (1979) • 3 BSD: first version to use virtual memory – the VAX-11 had a 32 -bit address space and only 4 MB of physical memory • 4 BSD first to integrate TCP/IP (1980) under ARPA funding
Historic Milestones (cont. ) • 4. x BSD introduced: – FAST File System (FFS) – Signals – Sockets • 4. 4 BSD (1993): last version from Berkeley • Berkeley Software Design, INC. was formed to market BSD
Commercial Releases • Sun. OS based on 4. 2 BSD introduced the NFS file system • Solaris from Sun based on SVR 4 • XENIX by Microsoft • AIX by IBM • HP-UX from HP • ULTRIX (Digital UNIX) from Digital first Multiprocessor UNIX
AT&T Releases • System III: 1982 • System V: 1983 - A different virtual memory architecture • System V Release 2 (SVR 2): 1984 • SVR 3: 1987 • Introduced interprocess communication, shared memory, semaphores, message passing, remote file sharing, shared libraries • SVR 4: 1989
SVR 4 Joint effort by AT&T and Sun • Integrates features from all other versions (SVR 3, 4 BSD, Sun. OS, XENIX) • Introduced real-time scheduling • AT&T sold its interest in UNIX to Novell in 1993
Solaris • Sun purchased SVR 4 rights in 1994 • Solaris was developed based on SVR 4 • Introduced: – A multithreaded kernel – Support for Multiprocessors
Mach • Introduced by Carnegie-Mellon University in 1986 • An implementation from Scratch to avoid the problems associated with UNIX’s legacy code • First Object-oriented operating system
Standardization • SVID (System V Interface Definition) from AT&T: 1984 • POSIX (Portable Operating Systems based on UNIX) from IEEE: 1986 • X/Open: 1990
Motivations for Change • Functionality – User-level tools and utilities – System functionality, e. g. interprocess communications, concurrency, advanced file systems • Networking – Distributed file systems – Client-server support – Distributed operating systems
Motivations for Change (cont. ) • Performance – Improved performance – Multiprocessor support • Hardware Changes • Quality Improvement • Paradigm Shift: – Server with terminals – Workstations – Client-server computing
Motivations for Change (cont. ) Specialized Applications: • Multimedia • Scientific Application • Embedded systems • Real-time systems
What Helped UNIX Grow? • • Initially free Open source Small kernel Simple approach to most functions Text representation of system data files Uniform (file-like) interface to all devices Portability
UNIX Weaknesses • • Did not stay simple The lack of a simple uniform user interface Small building block commands Too many (often incompatible) versions
LINUX “I am doing a (free) operating system (just a hobby, won’t be big and professional like GNU) for 386 AT clones” Linus Torvalds, 1991
LINUX • LINUX is a child of the Internet • Based on Minix (Unix-like educational operating system developed by Andrew Tanenbaum) • Based on open source philosophy • Originally developed by Linus Trovald • Enhanced and maintained by community of users
Reasons for LINUX Success • • Free Open Source Huge support network Frequent releases incorporating updates/fixes based on user feedback
LINUX Distribution • Free online download • Company-provided media for a fee only for the enhancements provided by the company • Current users estimated at 20 million
Table 2. 1 Web Resources (continued on next slide)
Table 2. 1 Web Resources (continued from previous slide)
Table 2. 2 Major LINUX Distributions
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