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Operating Systems
• Every computer has two fundamental components:
hardware and software
• The term hardware refers to the physical components
inside a computer
• A computer can have many different pieces of
Chapter 1
Operating Systems
• Software refers to the sets of instructions (programs) that
understand how to use the hardware of the computer in a
meaningful way
• More specifically, software programs use hardware to
manipulate data (or files) and perform useful tasks
• A program is a file stored on your computer, whereas a
process is that file in action, performing a certain task
Chapter 1
Operating Systems
• Two different types of programs are executed on a
– Applications, which are programs designed for a specific use
and that we commonly interact with, such as word
processors, computer games, graphical manipulation
programs, and computer system utilities
– The operating system (OS) software, which consists of a
series of software components used to directly control the
hardware of your computer
Chapter 1
Operating Systems
• The operating
system carries out
many different
tasks by
interacting with
many different
types of computer
Chapter 1
Operating Systems
• Command-line user interface: prompt where you must type a
command to tell the operating system what to do, or it can be a
• graphical user interface (GUI): consists of a series of visual
depictions of tasks known as icons that you may use to control
the operating system
• system services: programs that handle system-related tasks such
as printing, scheduling programs, and accessing the network
Chapter 1
The UNIX Operating System
• UNIX is an operating system that runs a variety of
different applications
• Similar to other operating systems, the UNIX
operating system loads into computer memory when
you first power on your computer and initializes all
the hardware components
Chapter 1
UNIX Provides a Standard Interface
The standard GUI in
UNIX is the Common
Desktop Environment
(CDE); however, some
UNIX flavors may use
other GUIs instead
such as MOTIF, GNU
Object Model
(GNOME), and K
Desktop Environment
Chapter 1
UNIX Provides a Standard Interface
In addition, all UNIX flavors offer
a text-based command-line
interface where you may type
commands that ultimately perform
useful commands on the system
The UNIX operating system
enables multiple users to access the
system simultaneously using
different user interfaces, hence, we
refer to UNIX as a multi-user
operating system
Chapter 1
UNIX Runs Many Applications
• UNIX was designed as a powerful application server that
can run for long periods of time without being shut down
• It has the capability to manage thousands of applications at
the same time; as a result, it is referred to as a multitasking
operating system
• The most common applications used on UNIX computers
include those listed on page 5 of the textbook
Chapter 1
UNIX Is Customizable
• UNIX supports the Shell and Perl programming languages,
which can be utilized to automate tasks or create custom
tasks that are then invoked as needed
• In UNIX you can simply write a short Perl script that uses
common UNIX commands and programs together to
achieve this task in only a few minutes
• Most UNIX configurations present hundreds of small
utilities, which, when combined with Shell or Perl
programming, can quickly and easily make new programs
that meet many business needs
Chapter 1
UNIX Roles
• All of the features of the UNIX operating system enable it
to function in different environments in a variety of roles,
– Network/Internet server
– File and print server
– Application server
– Supercomputer
– Scientific workstation
– Office workstation
Chapter 1
The History of UNIX
• Much of the research and development that led to the UNIX operating
system came from the Multiplexed Information and Computing
Service (MULTICS) project that was started in 1965 by the
Massachusetts Institute of Technology (MIT), General Electric (GE),
and AT&T Bell Laboratories
• Ken Thompson, one of the original researchers on the MULTICS
project, continued to experiment with operating system development
after the project was abandoned
• In 1969, he developed an operating system that ran on the Digital
Equipment Corporation (DEC) PDP-7 computer
Chapter 1
The History of UNIX
• Dennis Ritchie invented the C programming language that was used on
Ken Thompson’s UNIX operating system
• The C programming language was a revolutionary language at the time
• AT&T Bell Laboratories continued to develop new versions of UNIX
and sold the rights to use them to several different companies that in
turn marketed their own type of UNIX; these types are commonly
referred to as different UNIX flavors
• By the late 1970s, BSD UNIX was adopted as the primary operating
system for the U.S. Department of Defense Advanced Research
Projects Agency (DARPA)
Chapter 1
The History of UNIX
• In 1982, AT&T released System III UNIX (System I and II never
existed), and the University of California at Berkeley released BSD
UNIX version 3
• Both of these new versions of UNIX were based on version 7 of the
AT&T Bell UNIX, but they were very different in philosophy and
• By 1983, AT&T released System V UNIX (System IV was never
released), resulting in two distinct streams of UNIX at the time; the
AT&T System V stream and the BSD stream
• The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
created a standard called Portable Operating System Interface (POSIX)
in 1986 to address how operating systems interface with application
programs and to provide a way to standardize many of the different
UNIX flavors that appeared during this time
Chapter 1
The History of UNIX
In 1991, a Finnish student named Linus Torvalds released a free version of
UNIX called Linux
Since then, Linux has been freely and aggressively developed by volunteers
worldwide and is one of the most common UNIX operating systems used
In 1998, System V Release 5 evolved with the introduction of Santa Cruz
Operations (SCO) UnixWare 7, and, in 2000, Apple Computers Inc. introduced
the first user-friendly version of UNIX called OS/X
Chapter 1
Common UNIX Flavors
Chapter 1
The UNIX Development Timeline
Chapter 1
• Solaris is one of the oldest UNIX flavors available
• Bill Joy, the co-founder of Sun Microsystems, was the
original developer of BSD UNIX in the 1970s
• Solaris was initially called the SunOS when it was released
by Sun Microsystems in 1982 and is widely used in
academic and business environments today, primarily on
the SPARC and Ultra SPARC architectures
Chapter 1
• Sun Microsystems and Solaris have achieved great
fame in the past two decades for creating technologies
that have become standard across all UNIX; two of
these include the Network File System (NFS) for
sharing data files between UNIX computers and the
Network Information System (NIS) for sharing
configuration files between UNIX computers
Chapter 1
Hewlett-Packard UNIX (HP-UX)
• Since HP-UX was first released in 1986, it has
become one of the most popular UNIX flavors in
large-scale computing environments
• HP-UX runs primarily on the PA-RISC architecture,
but newer versions also run on the Intel Itanium
Chapter 1
UNIX Resources
• By far, the easiest way to locate resources on any topic is by
using a search engine such as where
you can simply put in a phrase representing what you are
searching for and receive a list of Web sites that contain relevant
• Each UNIX flavor is maintained by a certain company or
organization as discussed earlier in this chapter
• Because UNIX has been common in academic environments
since the 1970s, most university Web sites offer UNIX tutorials
and other useful information such as Frequently Asked
Questions (FAQs)
Chapter 1
UNIX Resources
• Web sites host valuable information, but most do not provide any
means for users to communicate with each other
• This functionality is provided by Usenet, which enables users to post
messages in forums called newsgroups and enables other users to read
and reply to those messages
• Newsgroups forums are grouped according to topic
• Posting to a newsgroup is often a very quick way to find the solution to
a problem, because people who read the posting are likely to have had
the same problem and found a solution
Chapter 1
• POSIX and the sharing of ideas have standardized most
features of different UNIX flavors
• Often the largest differences between UNIX flavors relate
to system hardware terminology, whereas most commands
are identical between UNIX flavors
• A wide variety of documentation and resources is available
for UNIX in the form of Internet Web sites, FAQs, and
• Certification is a valuable means of demonstrating
knowledge and ability to industry
Chapter 1