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Computer Architecture Overview

Jul 26, 2025

Overview

This lecture introduces the formal definition of computer architecture, explores its main components, and provides historical context with key figures who shaped modern computing.

Definition of Computer Architecture

  • Computer architecture is the design of computers, including instructions, hardware components, and system organization.
  • It is divided into Instruction Set Architecture (ISA) and Hardware System Architecture (HSA).

Instruction Set Architecture (ISA)

  • ISA determines how machine language programs interact with the computer.
  • ISA defines the set of instructions and their formats used by software to communicate with hardware.
  • Different computers can choose different ways to process operations like addition, based on their ISA.

Hardware System Architecture (HSA)

  • HSA deals with the organization of major hardware subsystems such as CPU, storage, and input/output.
  • It covers both logical design and data flow among subsystems.
  • Hardware is selected based on the ISA requirements (e.g., memory locations, add circuit).

Architecture vs. Implementation

  • Architecture specifies the design and functionality; implementation refers to building the design with specific technology, speed, and cost.
  • Multiple computers with the same ISA can run the same programs and are part of the same family.
  • Implementation and architecture influence each other but are distinct concepts.

Historical Context

  • Charles Babbage designed the Analytical Engine, the first proposed general-purpose computing machine.
  • Lady Ada Lovelace developed the first programming concepts for Babbage's machine.
  • Augustus De Morgan taught Ada Lovelace and contributed to Boolean algebra.
  • Alan Turing defined computability and is known as the father of computer science and AI.
  • John von Neumann designed the classic computer architecture, now called Von Neumann Architecture.
  • Von Neumann gathered leading thinkers post-WWII to advance computational theory.

Key Terms & Definitions

  • Computer Architecture — the design and organization of computer systems, including hardware and instructions.
  • Instruction Set Architecture (ISA) — the part of computer architecture defining supported instructions and their formats.
  • Hardware System Architecture (HSA) — the organization and logical design of hardware components.
  • Von Neumann Architecture — a computer design with stored programs and unified memory for instructions and data.

Action Items / Next Steps

  • Prepare for the next session on classifications of computer architecture.