The document introduces operating systems by defining their roles, services, components, and managers, highlighting their purpose in facilitating user interactions with computer hardware. It explains the perspectives from both users and systems, including the operating system's function in resource allocation, program execution, and error control. Additionally, it covers fundamental concepts such as the kernel, bootstrap program, computer system organization, and storage structure, emphasizing the importance of memory and storage hierarchy.

1. INTRODUCTION TO
OPERATING SYSTEM

2. OBJECTIVES
• To define the different services provided by the OS.
• Describe the purpose and functions of OS.
• Recognize the components and Managers of OS.
• List and compare the common desktop OS in use
today.

3. What is Operating
System?
You…, yes you, the gentlemen at
the back wearing white shirt

4. What is Operating
System?
• A program that acts as an intermediary
between a user of a computer and the
computer hardware
• Operating System is similar to a government….
government ???????

5. Operating System Goals
1. Execute user programs and make solving user
problems easier
2. Make the computer system convenient to use
3. Use the computer hardware in an efficient
manner.

6. What Operating Systems
Do?
• Let’s begin our discussion by looking at the operating
system's role in the overall computer system.
• But,,,,, what is the operating system's role in the
overall computer system?
You…, yes you, the lady at my left
side wearing jeans

7. Operating System Point of
Views
1. User View
2. System View

8. User View
• The user's view of the computer varies according to
the interface being used.
• Most computer users sit in front of a PC, consisting of
a monitor, keyboard, mouse, and system unit.
• Users want convenience, ease of use
• Don’t care about resource utilization
Is this right!, to be answered by the gentlemen
at the back wearing SCST dept. shirt

9. System View
• OS is a resource allocator
Manages all resources
Decides between conflicting requests for efficient
and fair resource use
• OS is a control program
Controls execution of programs to prevent errors
and improper use of the computer

10. Defining Operating
Systems
• In general, we have no completely adequate definition of
an operating system.
• The fundamental goal of computer systems is to execute
user programs and to make solving user problems easier.
• Toward this goal, computer hardware is constructed. Since
bare hardware alone is not particularly easy to use,
application programs are developed.

11. What is a kernel?
• The one program running at all times on the computer” is the
kernel.
• Everything else is either a system program (ships with the operating
system) or an application program. https://
www.youtube.com/watch?v=IvGdY6luTtU
• Kernel is the core of Operating System that provides basic services
to all parts of the OS
• Kernel loads first into memory when an operating system is loaded
and remains into memory until operating system is shut down again

12. Computer Startup
• bootstrap program is loaded
at power-up or reboot
Typically stored in ROM or
EEPROM, generally known
as firmware
Initializes all aspects of
system
Loads operating system
kernel and starts
execution
What is a Bootstrap program? and How
does it work

13. Computer System
Organization
• Focuses on how a computer system operates.
Note:
In studying operating system, we need a general
knowledge of the structure of computer system.

14. Computer-System
Operation
 One or more CPUs, device controllers connect through common bus providing
access to shared memory
 Concurrent execution of CPUs and devices competing for memory cycles

15. Computer-System
Operation
 I/O devices and the CPU can execute concurrently
 Each device controller is in charge of a particular device type
 Each device controller has a local buffer
 CPU moves data from/to main memory to/from local buffers
 I/O is from the device to local buffer of controller
 Device controller informs CPU that it has finished its operation by
causing an interrupt

16. Storage Structure
• Computer programs must be in main memory (also called random-access
memory or RAM) to be executed. Main memory is the only large storage area
(millions to billions of bytes) that the processor can access directly.
• Ideally, we want the programs and data to reside in main memory permanently.
This arrangement usually is not possible for the following two reasons:
1. Main memory is usually too small to store all needed programs and data
permanently.
2. Main memory is a volatile storage device that loses its contents when power
is turned off or otherwise lost.

17. Storage Structure
• Main memory – only large storage media that the CPU can
access directly
 Random access
 Typically volatile
• Secondary storage – extension of main memory that
provides large nonvolatile storage capacity.
 Magnetic disks, Flash drive, Magnetic Tape

18. Storage Hierarchy
• Storage systems organized in hierarchy
 Speed
 Cost
 Volatility
Did you know that…
The speed of a solid-state drive (SSD) can range from 500 MB/s to over 3,500 MB/s. This is
much faster than a hard disk drive (HDD), which typically has a speed of 30–150 MB/s.
Non-Volatile Memory Express (NVMe) SSDs are faster than SATA SSDs and can be the fastest
available storage. NVMe SSDs can transfer data at speeds of up to 20 gigabytes per second
(Gbps), which is more than three times faster than SATA SSDs

19. Storage-Device Hierarchy

20. Questions????