Timer alerts processor for a status scan of I/O device every 20 ms. I/O device interface has two 8-bit ports: status and data output.
Compute the time it takes to get the status and service the device, with an 8-MHz processor clock rate. All instructions take 12 clock cycles.
State your assumptions, if any.
As nothing is mentioned about the instructions executed during servicing the device, we assume that the processor simply reads the 8 bit data from the data output port of the device, in the name of ...
As nothing is mentioned about the activity during servicing the device, it is assumed that the processor simply reads out the 8 bit data from the data output port of the device, when servicing it.