Homework 6 solution

1.           A 32-bit computer has two selector channels and one multiplexor channel. Each selector channel supports two magnetic disk and two magnetic tape units.  The multiplexor channel has two line printers, two card readers, and five VDT terminals connected to it.  Assume the following transfer rates.

            Disk drive                               600 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
30 ns
IRQ6
50 ns
IRQ3
           

Time                Action

 

            0 ns:                 Start of Main Program

10    s:                IRQ1

 

 

 

 

 

 

 

 

If an address bus needs to be able to address eight devices, how many conductors will be required?
 

What if each of those devices also needs to be able to talk back to the I/O control device?

 

 

 

4.      Define the terms seek time, rotational delay, and transfer time. Explain their relationship.

 

 

5.      Suppose a disk drive has the following characteristics:

·         5 surfaces

·         1024 tracks per surface

·         256 sectors per track

·         512 bytes/sector

·         Track-to-track seek time of 8 milliseconds

·         Rotational speed of 7500 RPM.

 

a.       What is the capacity of the drive?

b.      What is the access time?

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