4.1 · Lesson 4 of 4
Interrupts
Syllabus 4.1.4
What this lesson covers
- Describe how interrupts are generated and handled
Key vocabulary
- Interrupt
- A signal sent to the CPU to tell it that an event needs attention.
- Interrupt service routine (ISR)
- A short program that handles a particular type of interrupt.
- Hardware interrupt
- An interrupt generated by a physical device, e.g. a key press or printer out of paper.
- Software interrupt
- An interrupt generated by a program or the OS, e.g. division by zero.
- Save state
- Storing the contents of the registers, including the program counter, so the program can resume later.
- Priority
- How urgent an interrupt is. Higher-priority interrupts are handled first.
- Interrupt queue
- Where interrupts wait to be handled: priority first, then first in, first out (FIFO).
- Polling
- The CPU repeatedly checking each device to see if it needs attention. Wastes processing time.
Check your learning
- Quick check: 4 questions
- Key vocabulary test: 8 terms
- Activity 1: Order the steps · drag and drop
- Activity 2: Types and queues · 8 questions
- Activity 3: Interrupts quiz · 8 questions