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Computer science Fully Summarized Notes
Laiba Gul
Chapter No 1
Overview of Computer System
Chapter 1: Overview of Computer System
This chapter introduces the fundamental components and operations of a computer system,
focusing on the synergy between hardware and software.
1. Core Definitions
• Computer System: A combination of hardware and software components that work together to
process data into useful information.
• Hardware: The physical, tangible devices of a computer system (e.g., keyboard, monitor, CPU).
Software: A set of instructions (programs) that tell the hardware how to perform specific
tasks.
2. Basic Operations of a Computer
A computer typically performs four basic operations:
1. Input: Accepting data.
2. Processing: Manipulating data.
3. Output: Displaying results.
4. Storage: Saving data for future use.
3. Classification of Computers
Computers are categorized based on their size, speed, and processing power:
• Supercomputers: The most powerful and expensive, used for complex tasks like weather
forecasting or nuclear research.
• Mainframe Computers: Large, powerful systems used by organizations (like banks) for bulk
data processing.
• Minicomputers: Mid-sized multi-user computers.
• Microcomputers: Personal computers (PCs, laptops) designed for individual use. Mobile
Computing: Portable devices like smartphones and tablets.
4. Software Categories
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The are two primary types of software:
• System Software: Programs that control the operation of the computer and its hardware (e.g.,
Operating Systems like Windows, device drivers).
• Application Software: Programs designed to help users perform specific tasks (e.g., MS Word,
web browsers).
• Firmware: Specialized software "embedded" into hardware (like a BIOS chip) that provides
low-level control for the device's specific hardware.
5. Software Licensing and Distribution
Understanding how software is distributed is crucial:
• Licensed/Proprietary Software: Software owned by a company; users must pay for a license to
use it (e.g., Microsoft Office).
• Open Source Software: Software whose source code is freely available for anyone to inspect,
modify, and enhance (e.g., Linux).
• Shareware: Software provided free of charge on a trial basis, often with limited features or a
time limit.
• Freeware: Software that is available for use at no monetary cost, though the creator retains the
copyright.
6. Input and Output (I/O) Devices
• Input Devices: Tools used to enter data into the computer, such as keyboards, mice, and
scanners.
• Output Devices: Tools that display or project the results of processing.
O Softcopy: Electronic output displayed on a screen (temporary).
Hardcopy: Physical output printed on paper (permanent).
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Chapter no 2
Computer Memory
Chapter 2: Computer Memory
This chapter covers how data is stored, categorized, and managed within a computer system.
1. Introduction to Computer Memory
• Definition: Computer memory is any physical device capable of storing information
temporarily or permanently.
• Memory Characteristics: Key attributes include storage capacity, access time (speed),
and cost per bit.
• Terminology: o Bit: The smallest unit of data (0 or 1). o Byte: A group of 8 bits.
o Word: The number of bits a CPU can process at one time (e.g., 32-bit or 64-bit).
2. Memory Built-up and Retention Power
• Volatile Memory: Loses its data when power is turned off (e.g., RAM).
Computer science Fully Summarized Notes
Laiba Gul
Chapter No 1
Overview of Computer System
Chapter 1: Overview of Computer System
This chapter introduces the fundamental components and operations of a computer system,
focusing on the synergy between hardware and software.
1. Core Definitions
• Computer System: A combination of hardware and software components that work together to
process data into useful information.
• Hardware: The physical, tangible devices of a computer system (e.g., keyboard, monitor, CPU).
Software: A set of instructions (programs) that tell the hardware how to perform specific
tasks.
2. Basic Operations of a Computer
A computer typically performs four basic operations:
1. Input: Accepting data.
2. Processing: Manipulating data.
3. Output: Displaying results.
4. Storage: Saving data for future use.
3. Classification of Computers
Computers are categorized based on their size, speed, and processing power:
• Supercomputers: The most powerful and expensive, used for complex tasks like weather
forecasting or nuclear research.
• Mainframe Computers: Large, powerful systems used by organizations (like banks) for bulk
data processing.
• Minicomputers: Mid-sized multi-user computers.
• Microcomputers: Personal computers (PCs, laptops) designed for individual use. Mobile
Computing: Portable devices like smartphones and tablets.
4. Software Categories
, 2
The are two primary types of software:
• System Software: Programs that control the operation of the computer and its hardware (e.g.,
Operating Systems like Windows, device drivers).
• Application Software: Programs designed to help users perform specific tasks (e.g., MS Word,
web browsers).
• Firmware: Specialized software "embedded" into hardware (like a BIOS chip) that provides
low-level control for the device's specific hardware.
5. Software Licensing and Distribution
Understanding how software is distributed is crucial:
• Licensed/Proprietary Software: Software owned by a company; users must pay for a license to
use it (e.g., Microsoft Office).
• Open Source Software: Software whose source code is freely available for anyone to inspect,
modify, and enhance (e.g., Linux).
• Shareware: Software provided free of charge on a trial basis, often with limited features or a
time limit.
• Freeware: Software that is available for use at no monetary cost, though the creator retains the
copyright.
6. Input and Output (I/O) Devices
• Input Devices: Tools used to enter data into the computer, such as keyboards, mice, and
scanners.
• Output Devices: Tools that display or project the results of processing.
O Softcopy: Electronic output displayed on a screen (temporary).
Hardcopy: Physical output printed on paper (permanent).
, 3
Chapter no 2
Computer Memory
Chapter 2: Computer Memory
This chapter covers how data is stored, categorized, and managed within a computer system.
1. Introduction to Computer Memory
• Definition: Computer memory is any physical device capable of storing information
temporarily or permanently.
• Memory Characteristics: Key attributes include storage capacity, access time (speed),
and cost per bit.
• Terminology: o Bit: The smallest unit of data (0 or 1). o Byte: A group of 8 bits.
o Word: The number of bits a CPU can process at one time (e.g., 32-bit or 64-bit).
2. Memory Built-up and Retention Power
• Volatile Memory: Loses its data when power is turned off (e.g., RAM).
