5
INTRODUCTION TO OPERATING SYSTEMS
MAT 324:-COMPUTER SYSTEM ORGANIZATION & PROGRAMMING
Edward M Kioko
Phone:+254-725-695-782
Email:Kioko@cuea.edu
Objectives of the Chapter

Define the term Operating system

Explain the functions of an operating system in a computer
system

Describe the common types operating systems

Understand the process and routines involved in computer
booting.

Explain the different modes of data processing
MAT 324 -IntroductionOperating Systems|MUIC
Definition of Operating System

A set of programs that manage the resources of
the computer as well as acting as an interface
between the user and the computer hardware.

A set of integration programs (routine) that are
used to manage as well as control the operation
of the hardware components of a computer
system.

Examples??
MAT 324 -IntroductionOperating Systems|MUIC
Functions of operating system

Input output management

Maintains a controlled input processing and output
processing.

Some memory is usually allocated for input data
only i.e. some locations hold data received from
particular input devices.

Other memory areas are allocated for output
buffering.

These locations hold data temporary before its final
transmission to specific output devices.
MAT 324 -IntroductionOperating Systems|MUIC
Functions of operating system

Input output management

Processor management
• OS usually allocates processor time
to the task executing in the main
memory.
MAT 324 -IntroductionOperating Systems|MUIC
Functions of operating system

Input output management

Processor management

Memory management
• The OS controls the usage of the memory space to
ensure that it is optimized.
• The OS will always take some memory space.
• The remain is usually taken up by the operating
application
• In a multiprogramming environment, the OS
usually maintain a dynamic table that stores data
about allocated and free main memory space.
• We call this table memory map.
MAT 324 -IntroductionOperating Systems|MUIC
Functions of operating system

Input output management

Processor management

Memory management

Backing storage management
• The OS uses device drivers to control the
operation of storage devices.
• Each device should have a device installed
• When a device is required to perform a
function, the OS is responsible for calling the
appropriate device driver that will take control
and coordinate the function of the device
MAT 324 -IntroductionOperating Systems|MUIC
Functions of operating system

Input output management

Processor management

Memory management

Backing storage management

Interrupt handling
• An event that alters the normal sequence of how
the processor executes its instruction’s that
instead of fetching the next instruction
• When an interrupt, OS will save the state of the
interrupt process then transfer control to the
most appropriate program.
MAT 324 -Introduction Operating Systems|MUIC 2022
Functions of operating system

Input output management

Processor management

Memory management

Backing storage management

Interrupt handling

Error correction
• The O.S should be able to handle errors that occur
as part of normal operating activity and not
programming errors.
• Example data lost during transfer because of an
interrupt to a routine should be available to recover
the data by setting up the read process again
MAT 324 -IntroductionOperating Systems|MUIC 2022
Functions of operating system

Input output management

Processor management

Memory management

Backing storage management

Interrupt handling

Error correction

Device allocation
• Several jobs may request the same output media.
• If more than one output devices are available for that
media, then some programs will be allocated one
device and other programs the other device.
MAT 324 -IntroductionOperating Systems|MUIC 2022
Functions of operating system

Input output management

Processor management

Memory management

Backing storage management

Interrupt handling

Error correction

Device allocation
•Preventing

File security and management
•Keeping track of files descriptions
illegal
access
or
amendments to system files
and locations.
MAT 324 -IntroductionOperating Systems|MUIC 2022
Functions of operating system







Input output management
Some transfers mainly handled between
the main storage direct access storage
Processor management
include
• Loading system software into main
Memory management
memory as required e.g. compiler
• Swapping applications programs or part
Backing storage management of the program between the main store
and main memory
• Bringing into main store and linking
Interrupt handling
together the applications or system
subroutines to be used in conjunction
Error correction
with
particular
job
e.g.
#include<iostream>;
Device allocation

File security and management

Loading programs and subroutines
MAT 324 -IntroductionOperating Systems|MUIC 2022
Functions of operating system

Input output management

Processor management

Memory management

Backing storage management

Interrupt handling

Error correction

Device allocation

File security and management

Log off events and operator communication

Loading programs and subroutines

Job scheduling
MAT 324 -IntroductionOperating Systems|MUIC 2022
Job
Priority
Creation Time
MAT 324 -IntroductionOperating Systems|MUIC
Process

It is an instance of a program under execution while a
program is whole batch of instructions.

A program may be subdivided into a number of processes
for execution.

New:-Process is being created outside the processor queue

Ready:-The process is waiting to be assigned the processor.

Running:-States whether instructions are being executed

Waiting:-The process waiting for some event to occur

Terminated:-The process finishes execution
MAT 324 -IntroductionOperating Systems|MUIC 2022
Processes states
MAT 324 -IntroductionOperating Systems|MUIC 2022
Modes of processing

Batch processing

Multiprocessing

Multiprogramming and multitasking

Multhreading

real time processing
MAT 324 -IntroductionOperating Systems|MUIC
Batch Processing (1)
MAT 324 -IntroductionOperating Systems|MUIC 2022
Multiprocessing (2)
MAT 324 -IntroductionOperating Systems|MUIC 2022
Multiprogramming (3)
MAT 324 -IntroductionOperating Systems|MUIC 2022
Multithreading (4)
MAT 324 -IntroductionOperating Systems|MUIC 2022
Real time (5)
MAT 324 -IntroductionOperating Systems|MUIC 2022
Distributed Data Processing (DDP) (5)
MAT 324 -IntroductionOperating Systems|MUIC
Steps of booting

CPU initialization.

BIOS attempts to access the first sector of the HDD(MBR)
which is a 512-byte sector is located in the first sector on the
disk.

The BIOS confirms there are a bootstrap loader/ boot loader
in the boot sector then loads it into memory (RAM).

BIOs hands over its work to the boot loader, which in turn
begins loading the operating system into memory.
MAT 324 -IntroductionOperating Systems|MUIC
Steps of booting (cont’d)

Boot loader turns control of the PC over to the operating
system. Then, the OS is ready for user interaction.

OS loads device drivers

This is the final stage in the boot process, after which the
user can access the system’s applications to perform tasks.
MAT 324 -IntroductionOperating Systems|MUIC