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Chapter 2

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.

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Chapter 2

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  1. Chapter 2 LINUX History

  2. Unix History “The number of UNIX installations has grown to 10, with more expected” - UNIX Programmer’s Manual, 1972

  3. UNIX as an Operating System • Run-time environment • System services • Utilities • Libraries • User programs

  4. Systems Supported by UNIX • Multiprocessor Computers • High Performance Computers • Work Stations • Personal Computers • Embedded Processors In short, all kinds of computers

  5. UNIX Variants • System V Release 4 (SVR4) by Novell, Inc. • University of California Berkeley UNIX (4.xBSD) • SUN OS • Solaris • Digital UNIX • HP-UX, XENIX, AIX, VENIX • Clones, such as Linux

  6. UNIX Variants Features Commonalities: • A core set of interfaces • A core set of features • Applications Differences: • Internal Implementation • Interface Semantics • Some features

  7. 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)

  8. 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

  9. Historic Milestones (cont.) • First 32 bit version developed for the VAX-11 (1978) and later evolved into 3BSD (1979) • 3BSD: first version to use virtual memory – the VAX-11 had a 32-bit address space and only 4 MB of physical memory • 4BSD first to integrate TCP/IP (1980) under ARPA funding

  10. Historic Milestones (cont.) • 4.x BSD introduced: • FAST File System (FFS) • Signals • Sockets • 4.4BSD (1993): last version from Berkeley • Berkeley Software Design, INC. was formed to market BSD

  11. Commercial Releases • SunOS based on 4.2BSD introduced the NFS file system • Solaris from Sun based on SVR4 • XENIX by Microsoft • AIX by IBM • HP-UX from HP • ULTRIX (Digital UNIX) from Digital first Multiprocessor UNIX

  12. AT&T Releases • System III: 1982 • System V: 1983 - A different virtual memory architecture • System V Release 2 (SVR2): 1984 • SVR3: 1987 • Introduced interprocess communication, shared memory, semaphores, message passing, remote file sharing, shared libraries • SVR4:1989

  13. SVR4 Joint effort by AT&T and Sun • Integrates features from all other versions (SVR3, 4BSD, SunOS, XENIX) • Introduced real-time scheduling • AT&T sold its interest in UNIX to Novell in 1993

  14. Solaris • Sun purchased SVR4 rights in 1994 • Solaris was developed based on SVR4 • Introduced: • A multithreaded kernel • Support for Multiprocessors

  15. 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

  16. Standardization • SVID (System V Interface Definition) from AT&T: 1984 • POSIX (Portable Operating Systems based on UNIX) from IEEE: 1986 • X/Open: 1990

  17. 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

  18. Motivations for Change (cont.) • Performance • Improved performance • Multiprocessor support • Hardware Changes • Quality Improvement • Paradigm Shift: • Server with terminals • Workstations • Client-server computing

  19. Motivations for Change (cont.) Specialized Applications: • Multimedia • Scientific Application • Embedded systems • Real-time systems

  20. 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

  21. UNIX Weaknesses • Did not stay simple • The lack of a simple uniform user interface • Small building block commands • Too many (often incompatible) versions

  22. 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

  23. 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

  24. Reasons for LINUX Success • Free • Open Source • Huge support network • Frequent releases incorporating updates/fixes based on user feedback

  25. 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

  26. Table 2.1 Web Resources (continued on next slide)

  27. Table 2.1 Web Resources (continued from previous slide)

  28. Table 2.2 Major LINUX Distributions

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