User program = 0 t = 10 t=40 Printer interrupt service routine t = 15 t=25 Figure 3.14 Example Time Sequence of Multiple Interrupts Communication interrupt service routine |||||||||| t = 35 t=25 Disk interrupt service routine

When a signal is received, the CPU suspends its current activity to process the request. The technique used in this instance is: A' Signal of Interrupt Spooling B C' Interrupt Handling D Polling.

Consider a CPU that operates with a data transfer rate of 30 Mbytes/s. The data is transferred byte-wise and the CPU has to transfer 30bytes of data, and the size of the Status register is 4 bytes. What is the total time needed to perform the data transfer?

A processor uses a serial link to communicate with a keyboard for word processing. A typist using this keyboard can type at rates peaking at 120 words per minute, where a word is 6 characters (including spaces and punctuation). The characters will be transmitted from the keyboard in 8-bit ASCII with one stop bit and no parity. Only consider these and no special characters. The programmer writes setup and polling service routines based on a minimum baud rate, but then finds that the keyboard will only interface at 19.2 Kbaud. Will the polling service routine have to change? Why or why not? Baud Rates 300 600 1200 2400 4800 9600 19200