CIT 140: Introduction to ITSlide #1 CSC 140: Introduction to IT Operating Systems

CIT 140: Introduction to ITSlide #2 Objectives To give an overview of the structure of a contemporary system. To describe briefly the structure and history of the UNIX operating system. To detain some important system setups.

CIT 140: Introduction to ITSlide #3 The Development of the UNIX Operating System Beginnings Research Operating System –UNIX Version 1 through UNIX Version 6 Developed and Written in C Releases distributed as C Source Code The design of the system allowed users to run multiple processes concurrently and to connect these processes with streams. AT& T System V –Released in 1983 Berkley Software Distributions –3BSD and 4BSD The History of Shells –Bourne Shell, C Shell, Korn Shell. Current and Future Developments - LINUX

CIT 140: Introduction to ITSlide #4

CIT 140: Introduction to ITSlide #5 Web Resources

CIT 140: Introduction to ITSlide #6 Computer System Hardware Main/ Primary Storage Central Processing Unit (CPU) Disk Bus I/O Devices

CIT 140: Introduction to ITSlide #7 Computer System Hardware

CIT 140: Introduction to ITSlide #8 Main/ Primary Storage Purpose: To store executing programs or processes. Also called Volatile Storage place. Units: bit, byte, KB, MB, GB, TB

CIT 140: Introduction to ITSlide #9

CIT 140: Introduction to ITSlide #10 Central Processing Unit (CPU) CPU executes the programs by fetching them from the RAM, one instruction at a time Every CPU has its own language called its instruction set A CPU is functionally divided into two parts –Control Unit –Execution Unit (or Arithmetic and Logic Unit (ALU)) The storage locations of CPU are called Registers

CIT 140: Introduction to ITSlide #11 Disk A storage place that contains all the computer system’s programs and applications A nonvolatile storage place Read and written in terms of sectors and blocks Latency Time Seek Time

CIT 140: Introduction to ITSlide #12 Bus A set of parallel wires used to carry information in the form of bits from one sub-system in a computer to another System Bus –Data Bus, address bus, control bus Loader Program Fetch, decode and execute operations form a machine cycle

CIT 140: Introduction to ITSlide #13 Machine Cycle

CIT 140: Introduction to ITSlide #14 UNIX Software Architecture Device Driver Layer Mouse driver, printer driver The UNIX Kernel –Process Management –File Management –Main Memory Management –Disk Management The System Call Interface Entry points to Kernel Language Libraries C, C++, Java, FORTRAN etc. UNIX Shell Applications Compilers, word processors, spreadsheets, ftp, telnet, Web browser etc.

CIT 140: Introduction to ITSlide #15 UNIX Software Architecture (Contd)

CIT 140: Introduction to ITSlide #16 Logging On and Logging Off Three basic ways of connecting to a UNIX operating system: –Local Area Network Connection –Internet Connection –Stand-alone Connection –

CIT 140: Introduction to ITSlide #17 Logging On and Logging Off (Contd)

CIT 140: Introduction to ITSlide #18 Correcting Mistakes

CIT 140: Introduction to ITSlide #19 Some Important System Setups