The document discusses the basics of operating systems and computer systems. It defines an operating system as a program that manages a computer's hardware and acts as an intermediary between the user and computer. A computer system consists of hardware components like the CPU and memory, an operating system, application programs, and users. The operating system controls hardware usage and coordinates application programs for users. It describes functions of the operating system like memory management, device management, processor management, file management, and security.

1. Unit -1
OPERATING SYSTEM BASICS AND COMPUTER SYSTEM OVERVIEW
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2. Operating System Basics
Definition:
An operating system is a program that manages a computer’s
hardware. It also provides a basis for application programs and acts
as an intermediary between the computer user and the computer
hardware.
Note : An amazing aspect of operating systems is how they vary in
accomplishing these tasks.
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3. Computer System Component
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Abstract view of the components of a computer system

4. Continue…
A computer system can be divided roughly into four components:
1. Hardware : CPU, Memory and I/O devices
2. Operating system: which governs the all processes.
3. Application programs: Word Processors, Spreadsheets and Web
browser
4. Users: People who use the computer system
Note: The operating system controls the hardware and coordinates
its use among the various application programs for the various users.
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5. Modern Computer
A modern general-purpose computer system consists of one or more
CPUs and a number of device controllers connected through a
common bus that provides access to shared memory
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6. Bootstrap Program
1. For a computer to start running—for instance, when it is powered
up or rebooted—it needs to have an initial program to run.
2. This initial program, or bootstrap program, tends to be simple.
Typically, it is stored within the computer hardware in read-only
memory (ROM) or electrically erasable programmable read-only
memory (EEPROM), known by the general term firmware.
3. It initializes all aspects of the system, from CPU registers to device
controllers to memory contents. The bootstrap program must know
how to load the operating system and how to start executing that
system.
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7. Functions of Operating System
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8. Continue…
The functions of an Operating System include:
1. Memory Management
2. Device Management
3. Processor Management
4. File Management
5. Security
6. Error Detection
7. Coordination among Software and Users
8. Job accounting
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9. Continue…
Memory Management
1. One of the main functions of OS is to manage the primary and secondary
memory. All the memory devices such as hard disk, pen drive etc. are managed
by OS.
2. Memory management keeps an eye on each and every memory location, in
any case either it is allocated or it is not allocated (free). Memory allocation to
the processes is also decided and checked by Operating System. It decides and
checks which process will obtain memory and at what time.
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10. Continue…
Device Management
1. An OS with help of their respective drivers manages device communication.
Following activities are performed by an Operating System for device
management:
2. It Keep a track of all devices. This task is performed by I/O controller.
3. It decides which process will get the device when and for how long.
4. It allocates and de-allocates the device efficiently.
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11. Continue…
Processor Management
In a multi-programming environment, it is OS who decides which
process will get the processor when and for how long. This task is
called Process Scheduling. Following activities are done by Operating
System for processor management:
1. It keeps a track of processor tasking and checks the status of
process. Traffic controller performs this task.
2. It allocates the processor and also de-allocates processor when a
process is complete and not required.
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12. Continue…
File Management
In a file system, generally directories are organized for usage and
easy navigation. Following activities are performed by an OS under
file management:
1. It keeps a track of location, information, status etc. This collective
is known as File System.
2. It decides who will get the resources.
3. It allocates and de-allocates the resources.
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13. Continue..
Security
An OS by using password and other similar techniques prevents and
checks unauthorized users to access the data and program.
Error Detection
By using various error detecting aids an operating system helps in
prevention of errors.
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14. Continue…
Coordination among Software and Users
It Coordinates and assigns
◦ Compilers
◦ Assemblers
◦ interpreters and other software to users.
Job accounting
It keeps a track of resources and jobs used by different users all the
time.
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15. References
1. Operating System Concept ninth Edition by Abraham Silberschatz and Galvin
2. https://electricalfundablog.com/operating-system-os-functions-types-resource-management/
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