UNIT-1
Introduction: Operating Systems
An operating system (OS) is a type of software interface between the user and the device
hardware. This software allows users to communicate with the device and perform the
desired functions. Operating systems use two components to manage computer
programs and applications.
Windows, Linux, and Android are examples of operating systems that enable the user to use
programs like MS Office, Notepad, and games on the computer or mobile phone.
Computer-System Organization
The organisation of the computer system consists of different units. All the units have
specific components designed to perform some particular task.
The units of the computer system are:
• Input Unit
• Output Unit
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, • Central Processing Unit (CPU)
• Storage Unit
• Input unit
All the information, data, or commands are provided to the computer systems as input
through input devices. The keyboard, microphone, scanner, or mouse are the input devices
that help the user enter the data in distinct forms.
The keyboard allows the user to enter input as characters, numbers, or symbols. Through
the mouse, you can select any file or folder. No matter in what form the input is entered, it is
changed into binary codes (machine language) of 1s and 0s. This is done as the computer can
only understand the machine language. Once the input has been received, then comes the
work of the Central Processing Unit (CPU).
• Output Unit
The output devices provide the result of the command provided to the computers. Monitor,
keyboard, printer are some of the output devices connected to the computer systems.
For example, if the user is writing something on the word processor through the keyboard,
it gets displayed on the monitor screen. Since the monitor screen provides the result, it is the
output unit.
• Central Processing Unit
After receiving the input through the input unit, the data goes to the CPU, where the complete
processing of the data occurs. The entered information and data are stored in the primary
memory, RAM (Random Access Memory), by the CPU. For processing, any data CPU takes it
from the RAM. Now CPU has its own three main components:
• Arithmetic Logic Unit
The function of the Arithmetic Logic Unit, as the name suggests, performs arithmetic and
logical operations. Once the input is entered, it is stored in RAM and sent to ALU for
processing.
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,After the arithmetic and logical operations are done, the output/result gets stored in primary
memory for a while. Then it is transferred to secondary memory, that is, a storage unit. From
there, it is sent to the output unit, which provides the output to the user.
• Control Unit
The function of the control unit is to get the information from the RAM (primary memory),
decode the data, and then implement them. Through the control unit, the CPU interacts with
the input/output device and the system’s memory.
The Control unit is one of the main components of the CPU. It is responsible for directing the
system’s operation by executing the program’s instructions.
• Register Set
The Register Set usually varies from one system to another. It includes a general-purpose
register that saves the output temporarily in the primary memory. The other registers are
special-purpose registers. Their work is to execute the programs.
• Storage Unit
As read above, the data or input that is entered is stored in the primary memory, i.e., RAM,
before the processing occurs. Even after the execution, the output is stored temporarily in
the primary memory and then in the second memory; it is sent to the output unit to provide
the results.
The storage unit is used to store all kinds of data at every processing step. The devices such
as hard disks allow the user to store data in different forms. A hard disk is a storage unit that
provides the computer with sufficient space to store data and programs.
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, Computer-System Architecture
Computer is an electronic machine that makes performing any task very easy. In computer,
the CPU executes each instruction provided to it, in a series of steps, this series of steps is
called Machine Cycle, and is repeated for each instruction. One machine cycle
involves fetching of instruction, decoding the instruction, transferring the data, executing
the instruction.
Computer system has five basic units that help the computer to perform operations, which
are given below:
1. Input Unit
2. Output Unit
3. Storage Unit
4. Arithmetic Logic Unit
5. Control Unit
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Introduction: Operating Systems
An operating system (OS) is a type of software interface between the user and the device
hardware. This software allows users to communicate with the device and perform the
desired functions. Operating systems use two components to manage computer
programs and applications.
Windows, Linux, and Android are examples of operating systems that enable the user to use
programs like MS Office, Notepad, and games on the computer or mobile phone.
Computer-System Organization
The organisation of the computer system consists of different units. All the units have
specific components designed to perform some particular task.
The units of the computer system are:
• Input Unit
• Output Unit
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, • Central Processing Unit (CPU)
• Storage Unit
• Input unit
All the information, data, or commands are provided to the computer systems as input
through input devices. The keyboard, microphone, scanner, or mouse are the input devices
that help the user enter the data in distinct forms.
The keyboard allows the user to enter input as characters, numbers, or symbols. Through
the mouse, you can select any file or folder. No matter in what form the input is entered, it is
changed into binary codes (machine language) of 1s and 0s. This is done as the computer can
only understand the machine language. Once the input has been received, then comes the
work of the Central Processing Unit (CPU).
• Output Unit
The output devices provide the result of the command provided to the computers. Monitor,
keyboard, printer are some of the output devices connected to the computer systems.
For example, if the user is writing something on the word processor through the keyboard,
it gets displayed on the monitor screen. Since the monitor screen provides the result, it is the
output unit.
• Central Processing Unit
After receiving the input through the input unit, the data goes to the CPU, where the complete
processing of the data occurs. The entered information and data are stored in the primary
memory, RAM (Random Access Memory), by the CPU. For processing, any data CPU takes it
from the RAM. Now CPU has its own three main components:
• Arithmetic Logic Unit
The function of the Arithmetic Logic Unit, as the name suggests, performs arithmetic and
logical operations. Once the input is entered, it is stored in RAM and sent to ALU for
processing.
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,After the arithmetic and logical operations are done, the output/result gets stored in primary
memory for a while. Then it is transferred to secondary memory, that is, a storage unit. From
there, it is sent to the output unit, which provides the output to the user.
• Control Unit
The function of the control unit is to get the information from the RAM (primary memory),
decode the data, and then implement them. Through the control unit, the CPU interacts with
the input/output device and the system’s memory.
The Control unit is one of the main components of the CPU. It is responsible for directing the
system’s operation by executing the program’s instructions.
• Register Set
The Register Set usually varies from one system to another. It includes a general-purpose
register that saves the output temporarily in the primary memory. The other registers are
special-purpose registers. Their work is to execute the programs.
• Storage Unit
As read above, the data or input that is entered is stored in the primary memory, i.e., RAM,
before the processing occurs. Even after the execution, the output is stored temporarily in
the primary memory and then in the second memory; it is sent to the output unit to provide
the results.
The storage unit is used to store all kinds of data at every processing step. The devices such
as hard disks allow the user to store data in different forms. A hard disk is a storage unit that
provides the computer with sufficient space to store data and programs.
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, Computer-System Architecture
Computer is an electronic machine that makes performing any task very easy. In computer,
the CPU executes each instruction provided to it, in a series of steps, this series of steps is
called Machine Cycle, and is repeated for each instruction. One machine cycle
involves fetching of instruction, decoding the instruction, transferring the data, executing
the instruction.
Computer system has five basic units that help the computer to perform operations, which
are given below:
1. Input Unit
2. Output Unit
3. Storage Unit
4. Arithmetic Logic Unit
5. Control Unit
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