System Interrupts (OCR A-Level Computer Science): Flashcards
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Interrupt
Interrupt
Signal to CPU that temporarily halts current process for urgent task
Purpose of interrupts
Purpose of interrupts
Respond to important events without waiting for current process; enables multitasking
ISR (Interrupt Service Routine)
ISR (Interrupt Service Routine)
Specialised instructions CPU executes in response to interrupt
Three types of interrupts
Three types of interrupts
Hardware, Software, Timer
Hardware interrupt trigger
Hardware interrupt trigger
External devices (keyboard, mouse, printer)
Software interrupt trigger
Software interrupt trigger
Software conditions like errors in program execution
Timer interrupt purpose
Timer interrupt purpose
Control process scheduling and time-sharing between tasks
What CPU saves during interrupt
What CPU saves during interrupt
State of current process including program counter
Interrupt vector table function
Interrupt vector table function
Identifies the ISR associated with specific interrupt
When CPU checks for interrupts
When CPU checks for interrupts
At end of each fetch-decode-execute cycle
What generates keyboard interrupt
What generates keyboard interrupt
User pressing a key
Why timer interrupts at regular intervals
Why timer interrupts at regular intervals
To allow OS to switch between processes for multitasking
Key benefit interrupts enable
Key benefit interrupts enable
Multitasking and timely responses to events
ISR relation to original program
ISR relation to original program
ISR is separate; original resumes after ISR completes
Why CPU saves state before ISR
Why CPU saves state before ISR
To ensure interrupted task resumes correctly