Computer Architecture Note Sheet
Introduction to Computer Architecture
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Definition: Computer architecture refers to the design and organization of computer
systems, including hardware and software components.
It involves the study of how computers are structured and how they operate.
Key Components of Computer Architecture
1. Central Processing Unit (CPU):
o The "brain" of the computer that executes instructions.
o Composed of control unit, arithmetic logic unit (ALU), and registers.
2. Memory:
o Primary memory (RAM) for temporary data storage.
o Secondary memory (e.g., hard drives, SSDs) for long-term storage.
3. Input/Output (I/O) Devices:
o Hardware interfaces for communication between the computer and external
devices (keyboard, mouse, monitor, etc.).
4. Bus System:
o A communication system that connects CPU, memory, and I/O devices.
o Types: Data bus, address bus, control bus.
Instruction Set Architecture (ISA)
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Defines the set of instructions that a CPU can execute.
Examples: CISC (Complex Instruction Set Computer) and RISC (Reduced Instruction Set
Computer).
CPU Organization
1. Control Unit:
o Manages the execution of instructions.
o Fetches, decodes, and executes instructions.
2. Arithmetic Logic Unit (ALU):
o Performs arithmetic and logical operations.
3. Registers:
o Small, high-speed storage within the CPU for temporary data storage.
o Examples: Program Counter (PC), Accumulator, Instruction Register (IR).
Memory Hierarchy
1. Cache Memory:
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High-speed memory located between CPU and RAM.
Stores frequently used data for faster access.
2. RAM (Random Access Memory):
o Volatile memory for active programs and data.
3. Virtual Memory:
o Extends RAM using secondary storage (e.g., hard drive) to manage large datasets.
Pipelining
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Technique to enhance CPU performance by overlapping instruction execution stages.
Stages: Fetch, Decode, Execute, Write Back.
Parallel Processing
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Using multiple processors or cores to perform tasks simultaneously for improved
performance.
Examples: Multi-core processors, GPUs.
Computer Architecture Trends
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Moore's Law: The observation that the number of transistors on a microchip doubles
approximately every two years, leading to increased computing power.
Energy Efficiency: Designing computer systems to consume less power.
Cloud Computing: Utilizing remote servers for computation and data storage.
Conclusion
Computer architecture is a crucial field that underpins the functioning of modern computing
devices. Understanding its fundamental concepts is essential for computer scientists, engineers,
and anyone interested in the world of technology.