Computer Architecture Basics

Operating Systems 1 - TECM 111

• Course title: Operating Systems 1
• Course code: TECM 111
• This course is part of Cloud Academy

Chapter 1: Introduction to Operating System

• Chapter outline:
  • Introduction
  • Computer system: overview and organization
  • OS History, objectives, services and interfaces
  • Operating System Structure: Architecture, Interrupt handling, System Call
  • Conclusion

II. Computer System: Overview

• Computer: electronic device for storing, retrieving, and processing data
• Composed of two main parts: hardware and software
• Hardware: Physical components
• Software: Set of programs to perform functions

II. Computer System: Organization

• Motherboard: Main circuit board, holds components (CPU, RAM) and connectors for other components
• Processor (CPU): Controls computer operations and processes data
  • Speed measured in Gigahertz (GHz)
  • Higher hertz = faster processing
• Control Unit: Directs and coordinates computer operations
• Arithmetic Logic Unit (ALU): Performs arithmetic, comparison, and logical operations
• Memories: Stores data and programs
  • RAM (Random Access Memory): Volatile memory, data lost when computer is shut down
  • ROM (Read-Only Memory): Non-volatile memory, stores startup instructions
  • Cache Memory: High-speed memory, acts as a buffer between RAM and CPU
• I/O Modules: Moves data between computer and external environment
  • Includes various devices like disks, communications equipment, and terminals
• System Bus: Circuit paths for transmitting data and signals among computer components
  • Three main types: Data Bus, Address Bus, and Control Bus
• Adapter Cards: Circuits allowing communication with peripherals (e.g., network card, video card)

III. OS History, objectives, services and interfaces

• 3.1 OS History: Computers and operation system evolution
  • First generation (1945-1955):
    • Computers were manual and relied heavily on physical components
    • No operating systems; programmers interacted directly with hardware
  • Second generation (1955-1965):
    • Improvements like Transistors
    • Less fragile and more efficient; batch operating systems, mainframes
  • Third generation (1965-1980):
    • Integrated circuits (ICs)
    • Introduction of Multiprogramming, leading to better resource utilization
    • Increased speed and efficiency
  • Fourth generation (1980-present):
    • Microprocessors: Faster processing, more reliable, and miniaturization
    • Sophisticated operating systems (MS-DOS, Macintosh, Windows, Linux)

III. OS History, objectives, services and interfaces Continued

• 3.2 Operating System: Objectives
  • The primary objective of an OS is to allow easy and efficient use of computer software and hardware
  • Achieve this by offering different services and a user interface

III. OS History, objectives, services and interfaces Continued

• 3.3 Operating System: Services
  • User/computer interface
  • Resource manager: Manages computer resources,
  • Program development: Facilitates the creation of programs (editors and debuggers)
  • Program execution: Manages execution of programs
  • Memory management: Manages memory allocation and utilization for programs
  • Access to I/O (Input/Output) devices: Enables programs to interact with various devices
  • Controlled access to files (File management): Manages files and directories
  • System access: Provides control and security to the system
  • Error detection and response
  • Accounting: Collecting usage statistics
  • Security: Protecting resources from unauthorized access via authentication

III. OS History, objectives, services and interfaces Continued

• 3.4 Operating System: Interfaces
  • User interface: Software layer enabling user interaction, includes command processor and visual components
  • Types of user interfaces:
    • Command-line interface
    • Graphical user interface (GUI)

IV. Operating System Structure: Architecture, Interrupt handling, System Call

• 4.1 Operating System Structure: Architecture
  • Monolithic operating system:
    • Simple structure, places all components (file management, memory management, etc.) directly within the kernel
  • Layered operating system:
    • Organizes components into layers, each layer communicating with layers above and below
  • Microkernel operating system:
    • Design where most components operate outside the kernel, with lower privilege level.
• 4.2 Interrupt handling:
  • External signals notifying the CPU about events, e.g., I/O device needs attention
  • Used to stop current tasks and execute a relevant procedure in the OS
• 4.3 System calls:
  • Programs instruct the operating system to perform operations on their behalf
  • Methods for requesting services from the operating system kernel.

V. Conclusion

• Overview of computer architecture and operating system importance
• History of operating systems
• Focus on hardware management in the next chapter

Test your knowledge on the fundamentals of computer architecture and the characteristics of various generations of computers. This quiz covers topics such as processor speed measurement, the functionalities of different computer units, and the advantages and disadvantages of early computing systems.