25 - CPU Sharing

Question 1

How can we have a multitasking system on a single processor ?

Answer 1

OS provides parallel processing by sharing the time of the CPU between different programs.

Question 2

What are the 2 main strategies to manage the CPU’s resources ?

Answer 2

• I/O breaks: while one program waiting for I/O to take place, another can use the CPU to execute instructions
• Time-slicing: CPU can switch rapidly between different programs executing a few instructions from each, using a period interrupt.

Question 3

What is the interrupt function called and where is called from?

Answer 3

Interrupt service routine (ISR) or Interrupt handler.

It is called from an event outside the normal program execution.

Question 4

Where is the relevant information about the interrupted program saved ?

Answer 4

Either on stack, or in the process control block.