Lernmaterialien für Chap 1 - "Athar Nada" an der El Shorouk Academy

• Faster than hard disks, nonvolatile
  • Various Technologies
  • Becoming More Popular

1. Execute User Programs and Make Solving User Problems Easier
2. Make The Computer System Convenient to Use
3. Use The Computer Hardware in an Efficient Manner

Each Processor is Assigned a Specie Task

Kernel

• Bootstrap Program is Loaded at Power-up or Reboot
  • Typically Stored in ROM or EPROM, generally Known as Firmware
  • Initializes all aspects of the system
  • Loads Operating System Kernel and Starts Execution
  
  

• Only Large Storage Media That The CPU Can Access Directly.
  • Random access
  • Typically volatile

• OS is a resources allocator
  • Manages all resources
  • Decides Between Conflicting Requests For Efficient and Fair Resource Use.
• OS is a control program
  • Controls Execution of Programs to Prevent Errors and Improper Use of The Computer

1. Users Want Convenience, Ease to Use, and Good Performance Regardless of Resource Utilization
2. Shared Computer Such as Mainframe or Minicomputer Must Keep all Users Happy
3. Users of Dedicate Systems Such as Workstations Have Dedicated Resources but Frequently Use Shared Resources From Servers
4. Handheld Computers are Resource-Poor, Optimized For Usability and Battery Life
5. Some Computers Have Little or no User Interface Such as Embedded Computers in Devices and Automobiles

1. Polling
2. Vectored Interrupt System 

1. Interrupt Transfers Controls to The Interrupt Service Routine Generally, Through The Interrupt Vector, Which Contains The Addresses of all The Service Routines
2. Interrupt Architecture Must Save The Address of The Interrupted Instruction
3. A Trap or Exception is a Software-Generated Interrupt Caused Either by ab Error or a User Request
4. An Operating System is Interrupt Driven

1. I / O Devices and The CPU can Execute Concurrently
2. Each Devices Controller is in Charge of a Particular Device Type
3. Each device controller has a local buffer
4. CPU Moves Data From/to Main Memory to / From Local Buffers
5. I / O is From The Device to Local Buffer of Controller
6. Device Controller Informs CPU That it Has Finished its Operation by Causing an Interrupt
7. One or More CPUs, Device Controllers Connect Through Common Bus Providing to Shared Memory
8. Concurrent Execution of CPUs and Devices Competing For Memory Cycles