In vectored interrupt scheme the interrupting device must send its identification through the data bus.
My doubt is which one is true?
- The device first gains control over the bus then it can send interrupt request and if the processor acknowledges this request then it will place the vector on the data bus.
- first the device raises the interrupt request and if its request gets acknowledged by the processor then it gains control over the data bus and sends the vector.
For the first point i think it is not true because we know that when a device sends interrupt request then the processor might be busy with the instruction execution, which may require the use of the bus, So if the first point is true then the processor can not use the bus because processor is not the master of the bus now. I think this is not true as processor executes its instruction that means it uses the data bus(may be!!) so by this reasoning i think 1st point is not true. am i right??