Operating Systems

Operating System acts as a middle man between the user and the computer hardware.

• Goals of the Operating System
  • Executes user programs and makes problem solving easier
  • Makes computer system convenient to use.
  • Use the hardware in an efficient manner.

Modeling an Operating System

• Operating System is a resource allocator
  • Manages all resources
  • Decides conflicting requests for efficient and fair resource usage
• Operating System is a Control Program
  • Controls execution of programs to prevent errors and improver use of the computer.
• Operating System has a Kernel part that does all operations

Real time Systems

• Real time systems are systems that need to run continuously and take decisions in a timely manner.
• Components involved
  • External Sensors and Actuators
  • Embedded Processors
  • Output Peripherals
• 2 broad categories
  • Open loop Systems
  • Closed loop Systems

Block Diagram of Embedded System

 

Open loop and Closed loop Systems

• Open loop Systems

  • Error factor is not taken into account
  • Not stable and output is unreliable

• Closed loop Systems

  • Error factor and external environment taken into account
  • More stable and output is accurate and reliable

 

Classification of Real time Systems

• Failure of a Real time system can bring operations to a standstill
• Embedded Systems range from day to day applications which include toys, electric toasters, etc
• 2 broad categories
  • Hard Real Time Systems
  • Soft Real Time Systems

Hard and Soft Real time Systems

• Hard Real time Systems

  • Failure to meet deadlines lead to catastrophe
  • Example would be an automatic flight control scenario

• Soft Real Time Systems

  • Failure to meet deadlines would not cause everlasting damages
  • Examples could range from a video game to washing machines, etc

Quick Note

• Real time systems are timely
• Systems can be classified broadly
  • Open loop
  • Closed loop
• Based on deadlines systems are
  • Hard real time
  • Soft real time