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1. Computer Glossary

1. Computer Glossary. User: You! The person working the computer. Computer: A machine which processes information by performing calculations and responding to inputs from users in a pre-programmed way.

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1. Computer Glossary

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  1. 1. Computer Glossary • User: You! The person working the computer. • Computer: A machine which processes information by performing calculations and responding to inputs from users in a pre-programmed way. • Computer System: The complete "informational environment" of the computer, including the computer itself, the users, and the information they communicate and process. • Interface: The ways in which two parts of the computer system communicate with each other.

  2. 2. Computer Glossary • Input: Information received by, or which goes into, a part of a computer system. • Output: Information sent by, or which goes out of, a part of the computer system. • I/0: Stands for Input/Output; all the information communicated through an interface. • Single User: A computer which be be used by only one person. • Multi-User: A computer which can be used by many people.

  3. 3. Computer Interfaces • Variety of Interfaces: Any two parts of a computer system communicate through an interface, for example: • A user and a computer (user interface); • One computer with another; • One part of a computer to another part of a computer; • One program with another; • Even one user with another!

  4. 4. Computer Interfaces • Over time the ways that users communicate with computers have matured.

  5. 5. Computer Hardware • Hardware: Refers to all the physical machines which are parts of the computer system. • Central Processing Unit (CPU): The central "brain" of the computer which performs the actual calculations. • Memory: A place to store information which can then be communicated to the CPU or to the user.

  6. 6. Computer Hardware • Permanent Memory: Large quantities of information stored on a disk drive for slower access. Mass Storage Systems • Temporary Memory: Smaller quantities of information stored electronically for faster access. Main Memory (RAM)

  7. 7. Computer Hardware • Peripherals: Accessory devices which transmit I/0 between the users and computer: • Input: Devices to get input into the computer • Mouse: Point-and-click input. • Keyboard: Typed input of 128 ASCII characters • American Standard Code for Information Interchange • CD-ROM: For Compact Disk-Read Only memory • Output:Devices to get output from the computer. • Monitor: Screen for displaying output. • Speakers: Sound output. • Printer: Output on paper.

  8. 8. Computer Hardware • Input/output: • Floppy Disks: Small quantities of permanent storage. • Hard Disks: Large quantities of permanent storage. • CD-ROM: Output to write-able CD-ROMs • Magnetic Tape: Largest quantities of permanent storage, sequential access. • Network: Communication in your office. • Modem or ISDN line: Communication with the world.

  9. 9. Computer Hardware • Terminal: Combination of a keyboard and monitor. • Necessary for command line interface

  10. 10. Computer Software • Software refers to the information stored in the hardware which makes it behave in a preprogrammed way. • Program: A set of instructions which tell the computer what to do; in what sequence; when certain events happen. • Computer Language: The general way in which instructions are recorded in the computer system. A computer may work with several computer languages simultaneously. • Syntax: The particular legal forms of instructions in any particular computer language.

  11. 11. Computer Software • Program Execution: Actually running the program, or performing the various steps in it. • Program Levels: One of the steps of a program might be to load and execute another program, which is said to be at a higher level. • Upper level program calls a lower level program to do something. • Results get sent to upper level program, which then continues.

  12. 12. Computer Software • Machine Language: A computer language only the machine can understand. • Lowest level language • for example: 00110011 • Source Language: A computer language which users can read. • Upper level language • has legal syntax • Example: for a=1

  13. 13. Computer Software • Process: Any program while it is actually in the act of running. • Single-Process Computer System: A computer system which can only run one application at a time. • Multi-Process Computer System: A computer system which can run many applications at a time. • A multi user system requires a multi process computer system.

  14. 14. Basic Unix Concepts • UNIX is: A combination of: • A multi-user, multi-process operating system; • A collection of utility programs (commands); • A command-line user interface. • File: A collection of information stored on disk and given a particular name and location on the disk. • Password: Secret word which will allow you to access your accounts.

  15. 15. Basic Unix Concepts • Account: Information kept about all allowed users, in particular their names, passwords, and files. • Session: The continuous time in which you are accessing your account. • Login: To begin your session by requesting access and providing your name and password. • Logout: To end your session. • Quits the shell

  16. 16. Unix Concepts Shell: The first UNIX utility program. • Responsible for providing an interface between the users and the UNIX utilities using the terminal • An application program with special responsibilities to provide this interface • A command-line interpreter

  17. 19. Basic Unix Concepts COMMAND AKA utility program, tool • Launches all other applications • Also a programming environment (scripts) SHELL O/S The Operating System HARDWARE

  18. 18. Kinds of Programs • Operating System (OS): The lowest level program, responsible for: • Transmitting the most primitive information among all the parts of the computer system (CPU, memory, peripherals); • Executing all the other programs at all higher levels. • Application Program: A higher level program which actually communicates with the user.

  19. 19. Kinds of Programs • Utility Program: A very small application program which does one very small task. • Compiler: A program whose job it is to translate another program from source language into machine language.

  20. 20. Basic Unix Concepts • Command: The name of a UNIX utility program. A command is typed by the user to the shell, and the shell loads and executes the named utility. • Each command is a utility program • Argument: Extra information given to a command.

  21. 21. Accessing a Unix System • There are terminal emulators that run on a PC to allow you to connect to a UNIX system. • This allows you to enter commands the same way you would if you were using a UNIX terminal.

  22. 22. The Unix System Prompt • Each system administrator can set a default system prompt. • Here at UNMLA, it is chicoma[1]% where the number inside the square brackets is your history number • Message of the Day (MOTD) • News • current system news • % news [-a][-n]

  23. 23. WhyUnix ??? • Open Source Code • Cooperative Tools and Utilities • Multi-User and Multi-Tasking Abilities • Excellent Networking Environment • Portability & Adaptability

  24. 24. What isUnix??? • The UNIX operating system is made up of several major components • The Kernel • The Shell • The File System • The Commands

  25. 25. What isUnix ??? USER SHELL KERNEL HARDWARE

  26. 26. The Unix Structure • Applications • Built using UNIX system commands, tools and programs • Horizontal applications • word processors • compilers • database management systems • spreadsheets • statistical analysis programs • communications programs

  27. 27. The Unix Structure • Applications continued • Vertical applications • industry specific • software packages used for managing • hotels • banks • point of sale terminals • Network applications • Internet Browsers • Multimedia applications

  28. 28. The Unix Structure • Commands • AKA utilities, user programs, tools • Executed by invoking their name through the shell • Standard utilities supplied with the UNIX system • text editing and processing • managing information • electronic communication and networking • performing calculations, etc

  29. 29. The Unix Structure • The File System • Provides logical method for organizing, storing, retrieving, manipulating and managing information • Hierarchical file system • files grouped together into directories • basic unit to organize information is a file • files occupy space on a disk • files are sequences of bytes

  30. 30. The Unix Structure • The Shell • Reads commands and interprets them as requests to execute a program • AKA Command Interpreter • Programming Language • allows user to control of how and when commands are carried out

  31. 31. The Unix Structure • The Kernel • the part of the operating system that interacts directly with the hardware of a computer using device drivers built into the kernel • Major functions • manage computer memory • control access to the computer • maintain the file system • handle interrupts & errors • perform input and output services • allocate the resources of the computer among users

  32. 32. The Unix Philosophy • A powerful and complex computer system should be • simple • general • extensible • UNIX treats directories, ordinary files, physical devices such as printers and disk drives, keyboard and monitors all in the same way -- as a file.

  33. 33. The Unix Philosophy • Allows you to use the same programs or commands that deal with ordinary stored files and use them for taking input from your terminal or displaying information on it.

  34. 34. The Unix Philosophy • UNIX is made up of a large collection of commands/tools which are small programs, each designed to perform a specific function, and all designed to work together. • UNIX provides many simple tools that can be combined to do a wide range of things.

  35. 35. The Unix Philosophy • Examples of UNIX Modularity • The Pipe | • Allows you to use the output of one command as the input of another. • Is used to join tools together to perform the tasks you need. • Standard Input and Output • UNIX treats input and output in a simple and consistent way.

  36. 36. History of Unix • Started as a research project • Has developed in to a powerful, flexible, and versatile operating system.

  37. 37. History of Unix • Late 1960’s: • MIT, AT&T Bell Labs and GE worked on an experimental operating system called MULTICS • Multiplexed Information and Computing System • Designed as OS for the GE 645 mainframe computer • Bell Labs dropped out of the project

  38. 38. History of Unix • 1969: • Ken Thompson (Bell Labs researcher) wrote new operating system on the DEC PDP-7 • Named it UNICS for Uniplexed Information and Computing System ;-) • Changed the name to UNIX in 1970 • multi-tasking and multi-user OS • included a command interpreter and some utilities

  39. 39. History of Unix • 1970: • AT&T Bell Labs agreed to finance the UNIX system • UNIX, an editor, and a text processing system called runoff was adopted by Bell Labs Patent Dept.

  40. 40. History of Unix • 1973: • Thompson and Dennis Ritchie rewrote the kernel in the C programming language • high-level language rather than in assembly language usually used for writing small computer operating systems • easier to maintain and port to other machines • code could be modified to individual preferences • offered UNIX OS to Universities, commercial firms and government agencies for a nominal cost.

  41. 41. History of Unix • 1977-1978: • 5th & 6th editions of UNIX released • many new tools and utilities • over 600 users • 1982: • UNIX System III (7th edition) released • AT&T’s first commercial release of UNIX • other versions were also available • often impossible to determine whether a particular feature was part of the mainstream UNIX system or just a part of one of the variants that might disappear.

  42. 42. History of Unix • 1983: • UNIX System V Release 1 • AT&T promised to maintain upward compatibility • programs built on Release 1 would continue to work on future releases.

  43. 43. History of Unix • Berkeley Software Distribution (BSD): • 1975: Grad students Bill Joy and Chuck Haley • editor EX • Pascal compiler • C Shell • screen oriented editor VI (an expansion of ex) • U.S. Dept. of Defense’s Advanced Research Projects Agency (DARPA): • Late 1970’s: based their universal computing environment on UNIX • Funded development of BSD UNIX

  44. 44. History of Unix • Berkeley Software Distribution (BSD): • Many vendors have used the BSD system as the foundation for the development of their own variants of the UNIX system • Sun Operating System (SunOS) developed by Sun Microsystems • With the incorporation of most of the important capabilities from BSD in UNIX System V Release 4, the BSD no longer has the wide influence it once had.

  45. 45. History of Unix • The XENIX System: • Introduced in 1980 by Microsoft • Brought UNIX system capabilities to desktop machines • Ported to many different microprocessors • Intel 8086, 80286, 80386 family • Motorola 68000 family • Santa Cruz Operation’s 80386-based machines • Provided a unified version of the UNIX OS that can run on desktops to supercomputers • Achieved the largest installation base of machines of all the early variants of UNIX.

  46. 46. History of Unix • The Unification of UNIX • Use of different versions of the UNIX system created problems for developers who wanted to create programs for a range of computers running the UNIX OS. • Standards were created to define the characteristics a system should have so that applications can be built to work on any system conforming to the standard.

  47. 47. History of Unix • UNIX Standards • The System V Interface Definition (SVID) • POSIX • X/OPEN

  48. 48. History of Unix • UNIX System V Release 4 • unified the most popular versions of the UNIX System, System V Release 3, the XENIX System, the BSD System, and the SunOS into a single package • conforms to the standards defined for UNIX System by various industry and governmental organizations • provided a single UNIX system environment • serves as the basis for the further evolution of UNIX.

  49. UNIX System V Release 4 Unified Command Set Supports 4 Shells V job Korn C The Directory Tree hierarchical directories accommodates network environments and remote file sharing 49. History of Unix

  50. UNIX System V Release 4 Input/Output and System Access makes it easier for programmers to use new devices introduced a common interface for system access through a terminal across a local area network by remote access 50. History of Unix

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