Chapter 2 Operating Systems 71
Application Software
Application software, also referred to as end-
user software, is designed for a specific purpose,
such as creating databases or spreadsheets,
word processing, producing graphics, or just for
entertainment. It is not an operating system.
Typical application software rely on the
operating system to communicate with PC
hardware such as the hard drive or CD-ROM
drive. When a word-processing program issues
a save command, the command is interpreted
by the operating system, which in turn passes it
through the CPU and on to the hardware. While
most 32-bit software applications will run on a
64-bit computer system, some will not. Antivirus
programs are a classic example of a software
application that must match the system type:
32-bit or 64-bit.
Software Driver
A software driver is a small package of
programs that allow proper communication
between the computer and the peripheral device.
Common devices that require drivers are printers,
modems, monitors, and storage devices. Software
drivers act as translators, converting common
commands issued from the CPU to the device in
use.
PC and software systems are constantly
evolving, but not necessarily in the same time
frame. For example, you may install a printer
that is much newer than the software installed
on a computer. The computer may not have the
software programs necessary to communicate
correctly with the printer. A typical scenario is
when a new printer is installed on a PC and the
self-test runs perfectly. However, when a file you
have created on the PC is sent to the printer, it
prints out a garbled set of meaningless symbols or
an endless stream of blank pages. This is a classic
case of incorrect driver software.
Software drivers are typically classified as
32-bit and 64-bit and are not interchangeable. You
must match the driver to the type of operating
system. Microsoft operating systems require
64-bit driver software to be digitally signed.
A digitally-signed driver contains a security
code which identifies and verifies the developer
of the software driver. Because the driver is
verified, Microsoft recognizes it as a driver from
a legitimate software vendor and that does not
contain malware.
Windows operating systems incorporate
options to allow you to run legacy software
applications and legacy drivers. The screen capture
in Figure 2-36 shows the options for configuring
a program to run as if it was installed on a
previous version of Windows. In this example,
the Battlefield 3 game is configured to run as
if it was installed on a Windows XP (Service
Pack 3) edition of the Windows operating system.
Microsoft provides a compatibility troubleshooter
called Program Compatibility, which automatically
detects possible compatibility problems associated
with various programs, Figure 2-37.
Software Patch
A software patch is a fix for operating
systems and application software that have
already been released. It also contains security
updates when the operating system or software
has been compromised. Although operating
Figure 2-36. Windows operating systems provide compatibility
options for configuring legacy software applications.