Computer-System Operation



  1. Hardware - Asynchronous
    Device informs CPU that something has happened e.g. a key has been pressed on the keyboard.
  2. Hardware - Synchronous
    CPU has tried to do something that has caused the interrupt. e.g. tried to read from an invalid memory location. (not always a problem, it may mean that that page is on disk needs to be fetched). Often called an Exception or Trap.
  3. Software
    CPU asked for the interrupt to happen. e.g. to perform an OS Call. Often called a Trap.

Hardware Interrupts

Interrupt Handling

I/O Calls

Blocking I/O

Non-Blocking I/O

Direct Memory Access (DMA) Structure

Storage Structure

Storage Hierarchy

Hardware Protection

Dual-Mode Operation

I/O Protection

Memory Protection

CPU Protection - how does the OS stay in control.

General-System Architecture