Organizational and Architectural Concepts in Computers

Chapter 1 Basic Concepts and Computer Evolution

Computer Architecture and Computer Organization

  • Computer Organization

    • Refers to the operational units and their interconnections that realize architectural specifications.
    • Highlights include:
    • Hardware details that are generally transparent to the programmer.
    • Control signals and interfaces between the computer and peripheral devices.
    • The technology used for memory.
    • The instruction set and the number of bits used to represent various data types.
    • Input/Output (I/O) mechanisms and techniques for memory addressing.

  • Computer Architecture

    • Arrangement of various components and their relationships that are visible to the programmer.
    • Architectural attributes include instruction set, data types, and computational methods.

  • Organizational Attributes

    • Describe non-visible system attributes important to performance impacts and resource management.

IBM System/370 Architecture

  • Introduced in 1970.
    • Included several model variants.
    • Supported upgrading to more expensive, faster models without discarding existing software.
    • Maintained architectural consistency to protect customers' software investments.
    • This architecture is still relevant as the foundation of IBM's mainframe products.

Structure and Function

  • Hierarchical System

    • Composed of interconnected subsystems.
    • Importance of Hierarchical Nature:
    • Essential for both design and description.
    • Designers may focus on only one system level at a time.

  • Definitions:

    • Structure: The interrelationship among components.
    • Function: The roles of individual components within the structure.

Basic Functions of a Computer

  • Four primary functions:
    1. Data Processing:
    • Involves various forms and processing needs.
    1. Data Storage:
    • Short-term Storage (e.g., cache, RAM) and Long-term Storage (e.g., HDD, SSD).
    1. Data Movement:
    • Input-Output (I/O): Data interchange with connected peripherals.
    • Data Communications: Transfers data over longer distances to remote devices.
    1. Control:
    • Managed by a control unit that directs resource management and the functioning of other parts based on instructions.

Main Structural Components of a Computer

  • Central Processing Unit (CPU):
    • Governs computer operations and carries out data processing.
  • Main Memory:
    • Temporary data storage.
  • I/O System:
    • Manages data transfer between the computer and external devices.
  • System Interconnection:
    • Mechanisms enabling communication among CPU, memory, and I/O systems.

CPU Components

  • Control Unit:
    • Manages CPU operations and the entire computer’s functions.
  • Arithmetic and Logic Unit (ALU):
    • Executes data processing operations.
  • Registers:
    • Provide internal storage for the CPU.
  • Interconnections:
    • Facilitate communication between the control unit, ALU, and registers.

Multicore Computer Structure

  • Central Processing Unit (CPU):
    • Fetches and executes instructions, features ALU, control unit, and registers.
  • Core:
    • Distinct processing unit within a processor chip; functions like a CPU in single-CPU systems.
  • Processor:
    • Physical silicon piece with one or more cores; executes and interprets instructions.
  • Multicore Processor:
    • Contains multiple cores, enhancing processing capabilities.

Cache Memory

  • Positioned between processor and main memory, smaller and faster than main memory.
  • Enhances memory access speed by storing frequently accessed data close to the core.
  • Employs multiple layers, such as Level 1 (L1), Level 2 (L2), Level 3 (L3) caches, ordered from closest to furthest from the core.

Historical Milestones in Computing

  • First Generation (Vacuum Tubes):
    • Utilized vacuum tubes for digital logic and memory.
    • IAS Computer:
    • Implemented the stored program concept credited to John von Neumann.
    • Completed in 1952, established foundational features for general-purpose computers.

Registers and Memory Archival

  • Registers facilitate data handling:
    • Memory Buffer Register (MBR): Holds data to/from memory; address specified by Memory Address Register (MAR).
    • Instruction Register (IR): Stores current instruction opcode.
    • Memory Address Register (MAR): Points to the address in memory for MBR actions.
    • Program Counter (PC): Keeps track of the next instruction to execute.

Instruction Types and Operations

Instruction Set Definition
  • Examples of instructions, opcodes and symbolic representations include:
    • Data transfer:
    • 00000000: LOAD M(X)
    • Unconditional branch:
    • 00001101: JUMP M(X,0:19)
    • Arithmetic operations:
    • 00000101: ADD M(X)

Integrated Circuits

  • Data Storage & Processing:
    • Provided by memory cells and gates (e.g., transistors).
  • Control Paths:
    • Enable movement of data and signal between components.
  • Transistors:
    • Serve as the cornerstone of digital circuits, governing states between conductive and non-conductive.
  • First integrated circuits allowed multiple transistors to be constructed from silicon simultaneously.

Moore’s Law

  • Proposed by Gordon Moore in 1965, predicting that the number of transistors on a chip doubles approximately every two years.
  • Impacts include:
    • Significant cost reductions in computer logic and memory manufacturing.
    • Increased processing speeds due to shorter electrical paths.
    • Size reduction for convenience and portability.