Tutorial that will give insight regarding operating system concept for beginners

1. By
Bhagyashri Katole
Bhagyashri Katole

2. 1. General overview of system
2. Kernel internals
3. Types of kernel
4. Unix architecture
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3.  The operating system is a set of programs that act as
a link between the computer and the user
 It allocate the system resources and coordinate all
the details of the computer's internal
 Objectives of OS
◦ Convenience
◦ Efficiency
◦ Extensibility
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4.  Regardless of structure, OS needs to securely
multiplex resources:
◦ protect applications from each other, yet
◦ share physical resources between them
 Also usually want to abstract away from hardware,
i.e. OS provides a virtual machine
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5. Virtual machine has following functions
 share CPU (in time) and provide each app with a
virtual processor
 allocate and protect memory, and provide
applications with their own virtual address space
 present a set of (relatively) hardware independent
virtual devices
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6. (Contd..)
 divide up storage space by using filing
systems, and
 do all this within the context of a security
framework
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7.  Kernel is central part of OS. It acts as interface
between user applications and hardware (CPU, Disk
& memory etc).
Operating System
Kernel
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8.  A kernel runs after the boot loader and is in control
of everything after it
 It manages various services as input and output
management, handling various call made to the
system known as system calls, etc.
 It resides on the low-level of abstraction
 When process makes the request of the kernel, the
request is called the system call
 Various kernel designs differ in how they manage
system calls and resources
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https://medium.com/@shrimantshubham/what-is-kernel-microkernel-
and-monolithic-kernel

10. Microkernel
 A microkernel is a software
or a program in which user
services and kernel services
are present in different
address space
 Smaller in size
 Easily extendible
 Examples - QNX, minix,
Symbian, Mac OS X,
L4Linux, Integrity, K42, etc.
Monolithic kernel
 A monolithic kernel is
program or a software in
which kernel services and
user services are present in
the same address space
 Bigger is size
 Not easily extendible
 Examples - Microsoft
Windows, Linux, BSD
(OpenBSD, NetBSD,
FreeBSD), Solaris, DOS,
OpenVMS, etc.
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11.  Users communicate with the kernel through a
program known as the shell
 The shell is a command line interpreter; it
translates commands entered by the user and
converts them into a language that is
understoodby the kernel
 Unix was originally developed in 1969 by a
group of AT&T employees Ken Thompson,
Dennis Ritchie, Douglas McIlroy, and Joe
Ossanna at Bell Labs
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12.  Unix variant available in the market
◦ SolarisUnix
◦ HP Unix
◦ BSD
◦ Linux - Freely available
 Unix is multiuser system i.e several people can
use a Unix computer at the same time
 Unix is also multitasking system i.e. A user can
also run multiple programs at the same time
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14.  The design of the UNIX operating system by Maurice Bach
 https://www.cl.cam.ac.uk/teaching/1011/OpSystems/os1a-
slides.pdf
 www.google.com
 https://techdifferences.com/difference-between-microkernel-
and-monolithic-kernel.html
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