Introduction Sakthivel Velusamy APCSE Before Linux v 1960

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Introduction Sakthivel Velusamy AP/CSE

Introduction Sakthivel Velusamy AP/CSE

Before Linux v 1960, Early stage of computation v Mainframes are the “computers” v

Before Linux v 1960, Early stage of computation v Mainframes are the “computers” v Innovating idea: Multi-programming & Multi-user § Create a multi-user & multi-program OS v 1964, Multics § Multiplexed Information and Computing Service 2 Sakthivel Velusamy AP/CSE

Before Linux: UNIX v. Many difficulties in Multics development v 1969 § Ken Thompson

Before Linux: UNIX v. Many difficulties in Multics development v 1969 § Ken Thompson • A simplified version of Multics UNIX § Dennis Ritchie • Rewrite the UNIX in C v. AT&T cannot sell the UNIX § UNIX is the first free Operating System 3 Sakthivel Velusamy AP/CSE

Before Linux: BSD v 1974 § § Berkeley University buy a tape of UNIX

Before Linux: BSD v 1974 § § Berkeley University buy a tape of UNIX Student start code navigation UNIX is customized and improved They call the OS as BSD (Berkeley Software Distribution) 4 Sakthivel Velusamy AP/CSE

Before Linux: Commercial UNIX v 1983, AT&T is splitted It can sell software v.

Before Linux: Commercial UNIX v 1983, AT&T is splitted It can sell software v. There is a great market for Operating System § Major hardware vendors need OS v. AT&T is selling UNIX System v 4 and licensing it § AIX for IBM, HP-UX for HP, … 5 Sakthivel Velusamy AP/CSE

Before linux v. In 80’s, Microsoft’s DOS was the dominated OS for PC v.

Before linux v. In 80’s, Microsoft’s DOS was the dominated OS for PC v. Apple MAC was better, but expensive v. UNIX was much better, but much more expensive. Only for minicomputer for commercial applications v. People was looking for a UNIX based system, which is cheaper and can run on PC v. Both DOS, MAC and UNIX were proprietary, i. e. , the source code of their kernel is protected v. No modification is possible without paying high license fees 6 Sakthivel Velusamy AP/CSE

GNU project §Established in 1984 by Richard Stallman, who believes that software should be

GNU project §Established in 1984 by Richard Stallman, who believes that software should be free from restrictions against copying or modification in order to make better and efficient computer programs §GNU is a recursive acronym for “GNU's Not Unix” §Aim at developing a complete Unix-like operating system which is free for copying and modification §Companies make their money by maintaining and distributing the software, e. g. optimally packaging the software with different tools (Redhat, Slackware, Mandrake, Su. SE, etc) §Stallman built the first free GNU C Compiler in 1991. But still, an OS was yet to be developed 7 Sakthivel Velusamy AP/CSE

Beginning of Linux § § § A famous professor Andrew Tanenbaum developed Minix, a

Beginning of Linux § § § A famous professor Andrew Tanenbaum developed Minix, a simplified version of UNIX that runs on PC Minix is for class teaching only. No intention for commercial use In Sept 1991, Linus Benedic Torvalds, a second year student of Computer Science at the University of Helsinki, developed the preliminary kernel of Linux, known as Linux version 0. 0. 1 8 Sakthivel Velusamy AP/CSE

Linux Today § Linux has been used for many computing platforms – § §

Linux Today § Linux has been used for many computing platforms – § § PC, PDA, Supercomputer, … Not only character user interface but graphical user interface is available Commercial vendors moved in Linux itself to provide freely distributed code. They make their money by compiling up various software and gathering them in a distributable format – Red Hat, Slackware, etc 9 Sakthivel Velusamy AP/CSE

Linux - free software v Free software, as defined by the FSF (Free Software

Linux - free software v Free software, as defined by the FSF (Free Software Foundation), is a "matter of liberty, not price. " To qualify as free software by FSF standards, you must be able to: § Run the program for any purpose you want to, rather than be restricted in what you can use it for. § View the program's source code. § Study the program's source code and modify it if you need to. § Share the program with others. § Improve the program and release those improvements so that others can use them. 10 Sakthivel Velusamy AP/CSE

FOSS v F stands for Free. § Free software comes without a cost to

FOSS v F stands for Free. § Free software comes without a cost to the user. v OSS stands for Open Source Software. v F. O. S. S. allows an individual the freedom and right to use software § Open source software can be used, studied and/or modified dependent upon the needs of the user and any modifications are still held to the open source guidelines and criteria. v Proprietary software is on the other end of the spectrum and is another name for non -free software and the coding is closed. 11 Sakthivel Velusamy AP/CSE