Chapter 1 - What is UNIX?

Quiz

1.       What are the two main versions of UNIX, and how did each begin?
UNIX System V is the evolutionary result of a project at AT&T Bell Laboratories. BSD UNIX is an offshoot version begun with an early distribution of AT&T UNIX by computer science students at the University of California at Berkeley.
2.       Write down five main functions of an operating system.
 
  • Provide a framework for executing programs
  • Share system resources (CPU, memory, disk) with other programs and users
  • Allow communication with devices (monitor, keyboard, network, printer, etc.) and other programs
  • Provide an interface for programs to access these functions
  • Provide utilities with which users can do useful work
    • 3.       What is the difference between a process and a program?
     
    A program is the machine instructions and data space it needs to run in order to perform a task. A process is a program that is being run.
    4.       What is the UNIX philosophy?
    A program should do one thing well. Complex problems should be solved by combining simple programs whenever possible. Write as little new code as possible leveraging existing code and utilities in order to solve a problem.
    5.       Who created UNIX?
    Many people have contributed to what is now known as UNIX. Ken Thompson and Dennis Ritchie of AT&T Bell Laboratories are generally credited with the design of the original version of UNIX that was written predominantly in the C language.
    6.       What makes UNIX an ìopenî system?
    The internal software architecture is well documented and adheres to standards. In addition, many distributions include the source code.

    Exercise

    1.1 Obtain a list of currently popular operating systems other than UNIX, and determine whether any of them could be serious contenders to UNIX. [level: medium]
    The major competitor to UNIX is Microsoft Windows XP. UNIX still competes with traditional ìmainframeî operating systems in some environments. VMS runs on both multi-user minicomputers as well as workstation platforms, so it is probably the second biggest competitor to UNIX.

    Project

    Investigate the MULTICS system, and find the similarities and differences between it and the UNIX system. [level: medium]
    MULTICS was considered the state of the art at the time Thompson and Ritchie began their work on UNIX and is generally considered to be their major inspiration. Though not in wide use today, it provided many facilities still considered important in operating systems.
    A good on-line resource for MULTICS is the MIT Multics Home Page:
     
    http://web.mit.edu/afs/net/user/srz/www/multics.html