Understanding how a computer works internally is essential for grasping how digital systems perform various tasks. In this unit, students will explore the basic architecture of a computer, focusing on its main components, memory structure, data flow, and number systems used for processing and storage.
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Central Processing Unit (CPU) – ALU, CU, and Registers
The Central Processing Unit (CPU) is considered the “brain” of the computer. It performs all major calculations and controls other parts of the system.
Arithmetic Logic Unit (ALU): This component performs all arithmetic operations (like addition and subtraction) and logical operations (like comparisons). It is the actual place where calculations take place.
Control Unit (CU): The CU acts like a supervisor. It manages and coordinates all parts of the computer by directing the flow of data and instructions between memory, ALU, and input/output devices.
Registers: These are small, fast memory locations inside the CPU that temporarily hold data, instructions, and addresses currently being used. They help in speeding up processing by storing frequently accessed information.
Together, the ALU, CU, and registers work in harmony to execute instructions and run programs.
Memory Hierarchy – Cache, RAM, and ROM
Computer memory is organized in a hierarchy based on speed, cost, and storage capacity. The closer the memory is to the CPU, the faster and more expensive it is.
Cache Memory: This is the fastest memory and is located inside or near the CPU. It stores frequently accessed instructions and data to reduce processing time.
RAM (Random Access Memory): This is the main memory of the system. It is volatile, meaning it loses its content when the computer is turned off. RAM temporarily stores data and instructions that the CPU is currently using.
ROM (Read-Only Memory): ROM is non-volatile memory that holds permanent instructions, such as the computer’s startup (boot) process. It cannot be easily modified and retains its data even when the power is off.
The memory hierarchy ensures that a balance is maintained between speed, performance, and cost efficiency.
System Bus – Data, Address, and Control Bus
A bus is a communication system that transfers data between components inside the computer.
Data Bus: Carries actual data between CPU, memory, and other devices.
Address Bus: Transfers memory addresses where data is stored or retrieved. It tells the system where to find the data.
Control Bus: Sends control signals to manage various operations like reading, writing, and interrupt requests.
These buses work together to ensure seamless data flow within the computer.
I/O Ports and Interfaces
Input/Output (I/O) ports and interfaces allow a computer to communicate with external devices like keyboards, printers, USB drives, and monitors.
I/O Ports: These are physical connections (such as USB, HDMI, Ethernet) that let external devices plug into the computer.
Interfaces: These include both the hardware and software mechanisms that enable data exchange between the computer and peripheral devices.
Interfaces help manage the data conversion and timing differences between the CPU and external hardware, ensuring smooth communication.
Number Systems – Binary, Decimal, Octal, Hexadecimal and Conversions
Computers understand and process data using number systems, particularly binary.
Binary (Base-2): Uses only 0 and 1. It is the core language of computers.
Decimal (Base-10): Uses digits 0–9. This is the number system used in everyday life.
Octal (Base-8): Uses digits 0–7. It is used in some computing applications for simplification.
Hexadecimal (Base-16): Uses digits 0–9 and letters A–F. It’s often used in programming and memory addresses for compact representation.
Conversions between these systems are crucial in computing. For example:
Decimal to Binary: Divide the number by 2 and record the remainders.
Binary to Decimal: Multiply each bit by powers of 2 and sum the values.
Hexadecimal to Binary: Replace each hex digit with its 4-bit binary equivalent.
Understanding these systems is essential for interpreting how data is stored, manipulated, and displayed in computing environments.