Software is a key component of any information
system. Of the total number of corporate dollars spent on computing, the software
share is increasing while the hardware share is decreasing. Typically,
different sizes of computers use different operating systems, and even the same
types of computers may not use the same operating system. The operating system
that a computer uses sometimes is called the software platform, or platform.
Application software packages often require a specific software platform. A
cross-platform application, however, is one that runs on multiple operating
systems.
Starting a
Computer
When you turn on a computer after it has been
powered off, you are performing a cold
boot. When you restart a computer that already has been powered on, you are
performing a warm boot. Your typically can perform a warm boot by pressing a
combination of keys on the keyboard (in Windows, CTRL+ALT+DEL), selecting
options from a menu, or pressing a Reset button on the computer.
If you watch the screen closely as the POST is
conducted, the value for the total amount of memory can be seen to change as it
is measured in the memory test. If the POST results do not match the data on
the CMOS chip, an appropriate message should appear. The boot program typically
is the first side, first track, and first sector of the hard disk. When you
install an operating system, one of the installation steps involves making an
emergency disk from which you can start your computer if the hard disk is
damaged.
User
Interface
You can interact with an operating system directly
(as you do when copying files, moving files, formatting disks, and so on) or
indirectly (as you do when working with an application program). An operating
system is intended to be transparent; that is, it does not have to be
understood, considered, or even known. The operating system with which an
application program will work is specified on the application software package.
The application programs you want to use should be considered before deciding
on an operating system, and the operating system must be considered when
choosing application software.
A graphical user interface is designed to be
easier to use (more user-friendly) than a command-line interface. As an example
of this user-friendly nature, consider how a relatively simple task, such as
deleting a file, is performed with a command-line interface and with a GUI. With
a command-line interface, you might type DEL
Features of
Operating Systems
Early operating systems were single user/single tasking, but today most operating system are
multitasking. Multitasking can be
cooperative, in which programs switch when they reach a logical break point, or
pre-emptive, in which programs switch based on priority and an allocated amount
of time. Early versions of Windows used cooperative multitasking; Windows 95
and subsequent versions use pre-emptive multitasking. Upon termination, most
programs relinquish their space in memory, which then is reallocated by the
operating system. Some programs, however, stay in memory after they terminate.
As a class, these programs are called TSR (Terminate and Stay Resident)
programs.
Virtual memory is employed with multitasking operating
systems to maximize the number of programs that can use memory at one time.
Paging, or the technique of swapping items between memory and storage, was
developed before processors could address directly more than 1 MB of memory.
All printers have buffers, and printer manufacturers are eager to sell DRAM.
The term spooling comes from the observation that placing print jobs
temporarily in a buffer is somewhat like winding thread onto a spool so that it
can be used at a later time. Today, adding and configuring devices is easier
because most devices support Plug and Play, which means the computer can
recognize a new device and automatically load the necessary drivers. A feature
of Windows 95, Plug and Play initially was greeted with mixed reviews. In fact,
some wags claimed the new technology was more accurately called, “Plug and
Pray.”
Processor utilization – the amount of time that the
processor is working and not idle – is one way of monitoring system
performance. In addition to the programs that come with most operating systems,
several utility programs are available to monitor system performance.
Formatting a disk is the process of preparing it for reading and writing.
Today, most floppy and hard disks are preformatted by the manufacturer. If you
format a disk that already contains data, the formatting process erases the
file location information, but it does not erase the actual files on the disk.
Therefore, if you accidentally format a disk, often you can unformat it with a
utility program. System security usually is most important for large systems or
networks. For single-user PCs, adequate system security can be a key in the
user’s pocket.
Stand-Alone
and Network Operating System
Many early operating systems were device dependent
and proprietary. Device-dependent operating systems run only on a specific type
of computer. Proprietary software is privately owned and limited to a specific
vendor or computer mode. Today, the trend is towards device-independent
operating systems that run on many manufacturers’ computers. Software that is
not proprietary (i.e., that can work with a variety of computer models)
sometimes is called portable or generic. Most of the operating systems
discussed in this section are portable. When an operating system is proprietary,
usually it is to boost hardware sales.
Operating systems for Apple computers and most
mainframes initially were proprietary. Steve Wozniak, cofounder of Apple
Computers, believes the decision to make its innovative Macintosh operating
system proprietary was one of the company’s greatest mistakes. “We had the most
beautiful operating system,” Wozniak writes, “but to get it you had to buy our
hardware at twice the price.” Wozniak now feels the operating system should
have been licensed.
Stand-Alone
Operating Systems
Bill Gates, founder of Microsoft and one of the
wealthiest men in the world, began his fortune with the MS-DOS operating
system. Although developed for IBM, Microsoft retained the rights to the
operating system and licensed the source code to several hardware
manufacturers, which resulted in multiple variations. An application written
for one type of DOS, however, will work with any other variation. A number
follows each version of PC-DOS or MS-DOS. The integer portion of the number
indicates a major release, while the decimal portion indicates updates. Thus,
MS-DOS 6.2 means major version six, which has been updated twice. To a great
extent, the popularity of DOS was a result of the large number of applications
written to work with the operating system.
Windows 1.0, released in 1985, was Microsoft’s
first attempt with a graphical user interface. It was not until five years
later, however, with the release of Windows 3.0, that computer users began to
take Windows seriously. Windows required 2 MB of memory (with 4 MB recommended)
and an 80386 or newer processor, so it could not be used with many older PCs.
Nevertheless, because Windows 3.0 was easier to use than DOS, eventually most
software was written, and many popular DOS programs were rewritten, to work
with Windows.
Despite the advantages of Windows 95 and a
heavily-funded promotional campaign, a poll of DOS and Windows 3.x users showed
not everyone immediately embraced the new operating system. When asked how
likely they were to adopt Windows 95 within the next six months, respondents
replied:
·
extremely likely 10%
·
possible 35%
·
not likely 53%
·
don’t know 2%
Why are
people often reluctant to adopt a new operating system?
The inclusion of Internet Explorer in the Windows
98 operating system led to an antitrust suit against Microsoft. Prosecutors
insisted that the incorporation of a browser was an attempt by Microsoft to
eliminate competition from rival Web browsers (such as Netscape Navigator).
Microsoft maintained that the addition simply was an enhancement to the
operating system. Although Microsoft advertised Windows 98 less heavily than
Windows 95, many vendors took up the slack. One retailer offered Windows 98
with the opportunity to buy a new computer for $98. The promotion evidently
worked. A buyer waited in line 11 hours for a chance to buy the new operating
system and discount computer. When asked if he would have come out simply for
Windows 98 (his current computer ran Windows 3.1), he replied, “Not a chance.”
Windows 2000 was released in February, 2000 and
was touted as a boon for all businesses, from small companies with no more than
two desktop computers to large corporations with vast networks. Windows
Millennium is a result of Microsoft’s recognition that the needs of business
and home users are different.
For years, the Macintosh operating system had
features that made it far easier to use than other operating systems. For
example, people could give files sensible names (like “Letter to Grandma”)
instead of the cryptic, eight-character strings (like “letgrand.txt”) demanded
by DOS and Windows 3.x. While Windows 95 incorporated many of these features,
Macintosh devotees still feel their operating system is easier to use. Until
recently, the Macintosh operating system was proprietary. In 1994 the operating
system was licensed, but experts feel Apple’s promotion has been lukewarm. New
standards let IBM computers run Apple software. More than 4,000 applications are
designed to run under the Mac OS. Microsoft has developed the more popular Mac
OS applications.
IBM supplies OS/2 (Operating System/2) Warp with
its high-end personal computers. OS/2 originally was developed jointly by IBM
and Microsoft to replace MS-DOS. As an interim measure, Microsoft developed
Windows, an operating environment to work with DOS. The eventual popularity of
Windows, coupled with the initial poor sales of OS/2, resulted in Microsoft and
IBM going their separate ways, with Microsoft concentrating on Windows and IBM
continuing to develop OS/2. Features offered in OS/2 Warp include:
·
An enhanced graphical user interface
·
Integrated business application software
·
Speaker-independent speech recognition software
·
Desktop objects that allow users to connect
directly to the Internet
·
Integrated Java programming language that allows
Java applications to run without a Web browser
·
Support for multiple CPUs using multiprocessing
Network
Operating Systems
Many consider UNIX to be the most portable
operating system. Although it has some shortcomings, UNIX often is used in
“turnkey” systems designed for retail stores, doctors, dentists, veterinarians,
and other small- to medium-businesses. Do you know what operating system is
mentioned in the film Jurassic
Park
Despite the current dominance of Windows, some
believe Linux is the operating system of the future. Because Linux is freeware,
users can modify and improve the program code. In addition, Linux is capable of
running efficiently with less powerful processors, even the 80386. The story of
Linux’s originator, Linus Torvalds, is told in the Technology Trailblazer on
page 8.25.
Embedded
Operating Systems
The latest Palm handheld computer, Palm IIIC,
offers a colour screen. When paired with a portable, expandable, attachable,
nearly full-sized keyboard and file compression software, some reviewers say
the Palm IIIC almost can replace a laptop. The Visor handheld computer runs the
same operating system as the Palm but offers several additional features –
videogames, cell telephone, modem, MP3 player, and two-way pager – at about
half the cost.
Utility
Programs
Utilities generally reside in storage until
summoned by the user or operating system kernel. Microsoft was the target of
several lawsuits for allegedly incorporating utility programs developed by
others into their DOS operating system. Some versions of DOS were modified
because of this litigation. In light of the ever-increasing number of utility
programs included with operating systems, will a market remain for separate
utility programs?
In addition to the utilities mentioned in this
chapter, other Windows 98 utilities include:
·
DirectX – Enhances multimedia capabilities on the
computer, providing better playback of different types of multimedia and
managing 3-D graphics better than console computers.
·
Drive Converter (FAT 32) – Converts the hard drive
to the FAT32 file system, an enhancement that stores data more efficiently,
creating extra disk space and helping programs run faster.
·
Registry Checker – Finds and fixes registry
problems each time the computer is started, automatically scanning the registry
for inconsistent data structures.
·
System File Checker – Keeps track of critical
files that make the computer run, restoring the files if they are moved or
changed.
·
Microsoft Magnifier – Makes the screen more
readable by displaying a magnified portion in a separate window and making it
possible to alter the colour scheme and contrast of the magnification window
for easier visibility.
Some
stand-alone utilities include:
·
Desktop enhancers – Change the desktop look and
organization, allowing users to create and switch between multiple desktops.
·
File conversion – Converts from one file format to
another so that a file can be used by another application.
·
Internet organizers – Helps in the management and
use of favorite Web sites, searching the Web and reporting on site changes.
·
Antivirus programs – Prevent, detect, and remove
computer viruses.
Some utility programs are used primarily by select
groups. For example, text editors -- utility programs that make it easy to work
with lists and records -- are popular with programmers and people who work with
databases. PC Tools and Norton Utilities are popular utility software packages
for personal computers.
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