Chapter Five: Using System Software
System Software Basics
2 types of software on your computer
Application Software is a system used for everyday tasks at home
System Software is a set of programs that help run the computer and
coordinate instructions between application software and computers
o System software consists of two programs: operating system and
What does an operating system do?
Operating System (OS) is a group of programs that controls how your
computer system functions
manages computers hardware, memory, storage devices, monitor and
responsible for the management, scheduling and coordination of tasks
system software includes utility programs. Utility program performs many
of the general housekeeping tasks for the computer
Do all computers have operating systems?
YES . . . OS is critical. Computer cannot operate without it
Are all operating systems alike?
Microsoft Disk Operating System (MS-DOS) (is a single-user operating
system) it was the first widely installed operating system in personal
Icons are pictures that represent an object
Single user to multitask which means to perform more than one process at
Types of Operating Systems (OSs)
Real-Time Operating Systems
Why do machines with built in computers need operating systems?
Real-time operating system (RTOS) allows repetitive series of specific
tasks to be performed in an exact amount of time
Require minimal user interaction
Where else are RTOSs in use today?
Fuel-injection systems, inkjet printers, VoIP phones, and medical devices
What kind of OS controls a simple cell phone?
OS systems that perform one task at a time
OSs for Networks, Servers, and Mainframes
What kind of OS do networks use?
Multiuser OS (network OS) which enables more than one user to access the
computer system at one time by efficiently handling and prioritizing requests
from multiple users Server is the computer on a network that manages network resources such
Examples: Linux and UNIX
UNIX is a multiuser, multitask, OS used as a network OS, primarily with
mainframes, although it is often found on PCs
What other kinds of computers require a multiuser OS?
Mainframe is responsible for storing, managing, and simultaneously
processing data from all users
Supercomputers use these as well
OSs for Mobile Devices
What kind of OS do smartphones use?
Smartphone has productivity features, in addition to features found on
personal media players and cameras, as well it connects to the web
Do gaming consoles and personal media computers require an OS?
Need a system software with system programs, called firmware, that control
the device as well as other programs that come with the personal media
player of gaming device
OSs for Personal Computers
What is the Microsoft Windows OS?
Began to work with MS-DOS
Windows XP provided networking capabilities
Windows 7, an OS, builds on security and user interface upgrades that the
Windows Vista release provided
What is the difference between the various editions of Windows 7 OSs?
Different editions, for home users, business users, and combination users
32-bit and 64-bit versions
What is the Mac OS?
Mac OS was the first commercially available OS to incorporate a graphical
user interface, with user friendly point-and-click technology
Does it matter what OS is on my computer?
Computers platform is the combination of the OS and processor
Microsoft Windows is not meant for a Mac and the Mac would not under
stand the Windows OS
Boot Camp, with the newest version of Mac OS X Snow Leopard, allows you
to run Windows on a Mac while also running OS X
Can I have more than one OS on my computer?
YES, due to the generous size of the hard drives
Linux is an open source OS designed for use on personal computers and as a
Linux OS is based on the central programming code of an OS
Where else is Linux used? Android (new OS developed by Google), and MeeGo (project between Nokia
Where can I get Linux?
Download for free
Some versions must be purchased
What the OS Does
Way to interact with the computer
Manages processor or CPU
Manages memory and storage
Manages systems hardware and peripheral devices
Provides consistent means for software applications to work with the CPU
The User Interface
How does the OS control how I interact with my computer?
OS provides a user interface which allows you to interact with the computer
Command driven interface is one in which you enter commands to
communicate with the computer system
Menu driven interface is one in which you choose commands from menus
displayed on the screen
What kind of interface do OS use today?
Graphical user interface (GUI) display graphics and use the point-and-click
technology of the mouse and cursor
Why does the OS need to manage the processor?
The OS must then switch among different processes millions of times a
second to make it appear that everything is happening seamlessly
How exactly does the OS system coordinate all the activities?
Event is an action to which to OS responds
Events can occur sequentially or other events involve two or more devices
OS switches back and forth
Interrupt handler is a special numerical code that prioritizes the requests
OS processes a task assigned higher priority before processing a task
assigned lower priority (preemptive multitasking)
Stack is a location in the RAM which stores a memo of what the CPU was
What happens if there is more than one document waiting to be printed?
The buffer is another temporary location in the RAM which stores a request if
the printer is trying to be used while it is already in use Request then waits in the buffer until the spooler, a program that helps
coordinate all print jobs currently being sent to the printer, indicates the
printer is available
When more than one print job is waiting than a line is formed so that they
can be processed in order
Memory and Storage Management
RAM as temporary storage area for instructions and data the processor
OS is responsible for coordinating the space allocations in RAM to ensure
that there is enough space for all of the pending instructions and data
OS than clears the data from the RAM when it does not need it
Does the amount of RAM on a system control the type of OS I get?
Not all applications and devices are compatible with 64-bit system
Can my system ever run out of RAM?
Ram has limited capacity, and eventually it will not respond well
As you add and upgrade software and increase your usage of the computer
system, you will likely find that the amount of RAM you once found sufficient
is no longer enough
What happens if my computer runs out of RAM?
If this happens the OS will borrow from the more spacious hard drive for
storing data, this is called virtual memory
Swap file is a temporary storage area on the hard drive where data is stored
that has not been recently used
The process of swapping data from the RAM to the swap file is know as,
Can I ever run out of virtual memory?
Thrashing is the condition of excessive paging
Solution to the problem is to increase the amount of RAM
How does the OS manage storage?
File-management system that keeps track of the name and location of each
file you save and the programs you install
Hardware and Peripheral Device Management
How does the operating system manage the hardware and peripheral devices?
Device driver is a special program that facilitates communication between
the hardware device and the operating system
commands that the operating system can understand
Do I always need to install drivers?
Plug and Play (PnP) is a software and hardware standard that Microsoft
created with the Windows 95 OS
including in the OS the drivers these devices need in order to run What happens if the device is not Plug and Play?
Printers are not plug and play
When you install a non-PnP device, you will be prompted to insert the driver
that was provided with the device
Can I damage my system by installing a device driver?
When you install a driver you system may become unstable
Roll back driver is on Windows and is a feature that removes a newly
installed driver and replaces it with the last one that worked
Software Application Coordination
How does the OS help application software run on the computer?
Application programming interface (API) are blocks of code that the CPU
recognizes that application software needs in order to interact with the OS
What are the advantages of using APIs?
When writing an application that can communicate with the OS, software
programmers only need to refer to the API code blocks
They make it easier for software developers to respond to changes in the OS
Many applications have the same API and therefore the same look
The Boot Process: Starting Your Computer
Boot process loads the OS into RAM
What are the steps involved in the boot process?
1. CPU activates BIOS
2. BIOS conducts power-on self-test
3. BIOS loads OS to RAM
4. Configuration and customization settings checked, and desktop displays
How can I tell if my computer is entering the data process?
Indicator lights and sounds in a Windows OS
On a PC with Windows or on a Mac, you will not hear any beeps or see any
keyboard lights. Rather, a PC or Mac logo will be presented
Step1: Activating BIOS
Activation of the basic input/output system (BIOS) which is a program that
manages the exchange of data between the OS and all the input and output
devices attached to the system
BIOS is stored in the ROM (read only memory) chip on the motherboard
Step2: Performing the Power-on Self-Test
How does the computer determine whether the hardware is working properly?
BIOS first ensures essential peripheral devices are attached and operational
(power-on self-test, also known as POST)
BIOS compares results of the POST with the various hardware configurations
that are permanently stored in CMOS CMOS complementary metal-oxide semiconductor is a special kind of
memory that uses almost no powe