Disk drive 700 Kbytes/s Magnetic tape drive 200 Kbytes Line printer 6.6 Kbytes/s
ID: 641584 • Letter: D
Question
Disk drive 700 Kbytes/s
Magnetic tape drive 200 Kbytes
Line printer 6.6 Kbytes/s
Card Reader 1.2 Kbytes/s
VDT 1 Kbytes/s
Estimate the maximum aggregate I/O transfer rate in this system.
2. Given the following set of events, show which routines the CPU is executing for times 0 to 100 ns. Each handler routine (with its interrupt request) takes 20 ns to complete. The priority of the interrupts ranges from IRQ6 as the highest priority interrupt to IRQ0 as the lowest priority interrupt.
Time
Action
0 ns
Start of main program
10 ns
IRQ1
25 ns
IRQ4
40 ns
IRQ6
50 ns
IRQ3
Time Action
0 ns: Start of Main Program
10s IRQ1
10
Time
Action
0 ns
Start of main program
10 ns
IRQ1
25 ns
IRQ4
40 ns
IRQ6
50 ns
IRQ3
Explanation / Answer
2)
As the interrupt will complete one instruction in 20 ns that means after 20nsec, a next interrupt will be handled no matter the previous one is completed or not, hence
0-10 ns-> IRQ1
10-35ns -> IRQ4
35-75ns->IRQ6
And in parallel to IRQ6, from 50ns, the IRQ2 will start
50-100 ns-> IRQ3