Question

Which one of the following is true for a $CPU$ having a single interrupt request line and a single interrupt grant line?

• A. Vectored interrupts are not possible but multiple interrupting devices are possible
• B. Neither vectored interrupt nor multiple interrupting devices are possible
• C. Vectored interrupt is possible but multiple interrupting devices are not possible
• D. Vectored interrupts and multiple interrupting devices are both possible

Answer 1

The correct option is A Vectored interrupts are not possible but multiple interrupting devices are possible

Consider the following figure:


In single line interrupt system contains a single interrupt request line and a interrupt grant line. In this system it may be possible that more than one output devices request interrupt at the same time for example $I/O$ port $0$ to $I/O$ port $n$ may request an interrupt at the same time but only one request will be granted according to priority. So, In single interrupt system vectored interrupts are not possible but multiple interrupting devices are possible.