Introduction to Information Systems Engineering
3. System Software
System Software
● Works with end users, application programs, and computer hardware to
handle many details relating to computer operations.
● Includes:
Operating systems coordinate resources, provide an interface
between users and the computer, and run programs.
Utilities perform specific tasks related to managing computer
resources.
Device drivers allow particular input or output devices to
communicate with the rest of the computer system.
Language translators convert programming instructions into a
language that computers understand and process.
2
Outline
● Computer System and Operating System
● Functions of Operating System
● Categories of Operating Systems
● Utilities
3
Computer System and Operating System
Operating System
● A program that acts as an intermediary between a user of a computer
and the computer hardware.
● Operating system goals:
Executing user programs and make solving user problems easier.
Making the computer system convenient to use.
Using the computer hardware in an efficient manner.
● Items necessary to understand the role of the operating system:
Computer System Structure
Computer System Organization
4
Computer System and Operating System
Computer System Structure
Operating system and other components of the computer system
● Hardware: provides basic computing resources
CPU, memory, I/O devices
● Operating system: controls and coordinates use of hardware among
various applications and users
● Application programs: define the ways in which the system resources
are used to solve the computing problems of the users
word processors, compilers, web browsers, database systems
● Users
People, machines, other computers
5
Computer System and Operating System
Image of Computer System
user 1
text editor
user 2
user 3
compilers
web browsers
…
…
Application programs
Operating System
Computer hardware
user n
database systems
Computer System and Operating System
Computer System Organization
CPU
Disk
Controller
USB
Controller
Display
Adaptor
System Bus
Memory Unit
7
Computer System Organization
● CPU (Central Processing Unit): An electronic circuit that executes
instructions that make up a computer program.
● System Bus: A communication path that exchanges data from the CPU
to other components of the computer.
● Memory Unit: A computer component where the CPU stores data and
instructions
(Details will be introduced in the 6th week. )
8
Outline
● Computer System and Operating System
● Functions of Operating System
● Categories of Operating Systems
● Utilities
9
Functions of Operating System
● Process Management
● Memory management
● File Management
● Device Management or I/O Management
● Security & Protection
● User Interface Mechanism
10
Functions of Operating System
Process Management
● A process is a program in execution. It is a unit of work within the
system.
● Process needs resources to accomplish its task.
● When multiple processes exist in the system and require the same
resources at the same time, the operating system must manage all
processes and resources in a convenient and efficient way.
11
Process Management
Process State
The process, from its creation to completion, passes through various
states. The process may be in one of the following states during
execution.
● new: The process is being created
● running: Instructions are being executed
● waiting: The process is waiting for some event to occur
● ready: The process is waiting to be assigned to a processor
● terminated: The process has finished execution
12
Process Management
Diagram of Process State
13
Process Management
● The created process automatically goes from new state to ready state
in most desktop computer systems.
● If there are multiple processes in the ready state, the process
selected by the scheduler is assigned to the CPU by the dispatcher
and becomes the running state.
● A process in the running state will be in the terminated state when it
completes execution or is explicitly being killed.
● A process in the running state becomes ready state by an interrupt.
● A process in the running state will be in the waiting state when it
requests execution of input / output.
● A process in the waiting state will be in the ready state when the
/ O execution is completed.
I
14
Functions of Operating System
Memory management
● Memory is a large array of words or bytes, each with its own
address.
● To execute a program all (or part) of the instructions must
be in memory.
● All (or part) of the data that is needed by the program must
be in memory.
15
Memory management
About Memory
● Hardware view: Electronic circuits to store and retrieve
information.
● The Bit (binary element) is the storage unit, the byte (8 bits) is
the addressing unit.
● Word is a natural unit of data used in a particular processor
design.
The largest amount of data a processor can transfer to and
from memory in a single operation is words.
Word sizes are typically 32-bits or 64-bits on modern
general-purpose computers.
16
Memory management
Memory management activities
● Keeping track of which portion of memory are currently being
used and who is using them.
● Determining which processes and data to move into and out of
memory.
● Allocation and deallocation of memory blocks as needed by
the program in main memory. (Garbage collection).
17
Functions of Operating System
File Management
● A file is a collection of related information defined by its creator.
● File systems provide the conventions for the encoding, storage and
management of data on a storage device.
● File management activities:
Creating and deleting files and directories
Primitives to manipulate files and directories
Mapping files onto secondary storage
18
Functions of Operating System
Device Management
● Device management in an operating system means controlling the
Input/Output devices like disk, microphone, keyboard, printer,
magnetic tape, USB ports, camera, scanner, other accessories.
● A process may require various resources, including main memory,
file access, and access to disk drives, and others.
If resources are available, they could be allocated, and control
returned to the CPU.
Otherwise, the procedure would have to be postponed until
adequate resources become available.
19
Functions of Operating System
Device Management Activities
● Keeping tracks of all devices connected to system.
Program responsible for this task is known as the I/O
controller.
● Deciding which process gets access to a certain device and for
how long.
● Allocating devices in an effective and efficient way.
● Deallocating devices when they are no longer required.
20
Functions of Operating System
Security & Protection
● Protection: any mechanism for controlling access of processes or
users to resources defined by the Operating System.
● Security: defense of the system against internal and external
attacks
● Threats to Protection and Security
Virus
Trojan Horse
Trap Door
Worm
21
Security & Protection
Protection Methods
● Authentication: the process of recognizing or identifying a user’s
identity whether it is true, real, or not.
● Authorization: Ensuring whether the user has access permission.
● Biometric system: Verifying the user’s identity based on several
important characteristics that are physiological and behavioral
features.
● Firewall: A method of network security that prevents the computer
network from users that are not authorized to have access to a
network. Firewalls can either be hardware or software or both.
22
Functions of Operating System
User Interface Mechanism
● A user interface (UI) controls how you enter data and instructions
and how information is displayed on the screen.
● Two types of user interfaces
Command Line Interface
Graphical User Interface
23
User Interface Mechanism
Command Line Interface
● A command-line interface (CLI) processes commands to a
computer program in the form of lines of text.
● CLI is generally used by using a terminal emulator.
● Well known terminal emulator:
Windows PowerShell for Windows
Terminal for macOS
an example of
Terminal
(Details will be introduced
in weeks 4 and 5. )
24
User Interface Mechanism
Graphical user Interface
● The graphical user interface (GUI) is a form of user interface that
allows users to interact with electronic devices through graphical
icons and audio indicator such as primary notation, instead of
text-based user interfaces
● macOS
Aqua: The trade name for the graphical user interface (GUI)
appearance of Apple's Mac OS X and macOS operating systems.
● Windows
Universal Windows Platform (UWP): A GUI builder that
simplifies the creation of GUIs by allowing the designer to
arrange graphical control elements.
25
Outline
● Computer System and Operating System
● Functions of Operating System
● Categories of Operating Systems
● Utilities
26
Categories of Operating Systems
● Embedded operating systems
RTOS (real-time operating systems)
Operating systems stored within the device.
● Stand-alone operating systems
Desktop operating systems
Operating systems which control a single desktop or laptop
computer.
Operating systems located on the computer’s hard disk.
● Network operating systems
Operating systems which are used to control and coordinate
computers that are networked or linked together.
27
Categories of Operating Systems
Mobile Operating Systems
● A type of embedded operating system.
● Two of the best known.
Android was developed by Google.
▪ It is used as the operating system for some of the most
popular cell phone.
iOS was developed by Apple.
‧ It is used as the platform for Apple’s mobile devices.
28
Categories of Operating Systems
Desktop Operating Systems
● Windows
● MacOS
● UNIX
● Linux
29
Desktop Operating Systems
Windows
● It is designed to run with many different microprocessors.
● Windows 10 is currently the most widely used Windows series
operating system.
● The most recent version is Windows 11.
macOS
● An innovative, powerful, easy-to-use operating system
● It runs on Macintosh computers.
● macOS Monterey 12, macOS Ventura 13
30
Desktop Operating Systems
UNIX
● It was originally designed to run on minicomputers in network
environments.
● It is widely used by servers on the web, mainframe computers,
and very powerful personal computers.
Linux
● It is an operating system that extended one of the UNIX versions.
● It is open-source software.
31
Outline
● Computer System and Operating System
● Functions of Operating System
● Categories of Operating Systems
● Utilities
32
Utilities
● Specialized programs to make computing easier
● Most essential utilities
Troubleshooting or diagnostic programs
▪ Recognizes and correct problems
Antivirus programs
▪ Guard your computer against viruses
Backup programs
▪ Copies of files to restore if necessary
File compression programs
▪ Reduces the size of files for more efficient storage
33