1. (20 points) 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 ten VDT terminals connected to it. Assume the following transfer rates. Disk drive 800 Kbytes/s Magnetic tape drive 200 Kbytes/3 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. (20 points) 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 IRQ5 20 ns IRQ4 35 ns IRQ3 50 ns IRQ2 Time Action

0 ns: Start of Main Program 10 ns: IRQ5

3. (20 points) Create a page translation table the meets the requirements of the virtual memory system shown below. Assume page (and frame) sizes of 5 with pages 0 through 3 in logical memory and frames 0 through 7 in physical memory. (Hint: Similar to Self-Assessment Question 7)

Logical Memory Physical Memory

0 A 0

4 5 9

1 B 10 B

19 20 24 25

29 A 30

34 35

39 40

Page Frame

2 4. (20 points) A computer system with 16K of memory, a Memory Management Unit with a page size of 2000, and the following page translation table (all numbers in hexadecimal):

Logical Address Physical Start 0000 10000 2000 1F000 4000 2C000 6000 22000 8000 30300 A000 41600 C000 81000 E000 3F000

a. Indicate the physical memory location corresponding to logical address 8050.

b. Indicate the logical address corresponding to physical memory location 23123.

5. (2 points) The most efficient type of I/O is ______. a) Direct Memory Access (DMA) b) Programmed I/O c) Programmed I/O with Interrupts

6. (2 points) “Printer ready for more data” would trigger a(n) ______. a) External event interrupt b) Event completion interrupt c) Time allocation interrupt d) Abnormal event interrupt

7. (2 points) A keyboard with input data would trigger a(n) ______. a) External event interrupt b) Event completion interrupt c) Time allocation interrupt

3 d) Abnormal event interrupt 8. (2 points) Dividing by 0 would trigger a(n) ______. a) External event interrupt b) Event completion interrupt c) Time allocation interrupt d) Abnormal event interrupt

9. (6 points) Answer the following statements as True/False

a) ______DMA allows the CPU to perform other tasks during I/O transfer.

b) ______DMA can transfer only in one direction.

c) ______DMA transfers large blocks of data to and from the CPU

10. (8 points) Match the descriptions below with the most appropriate memory management scheme (A through D). Answers may be used once, more than once, or not at all. A. Fixed-partition multiprogramming B. Single task or uniprogramming system C. Variable-partition multiprogramming D. Virtual memory systems

______a) allows program to exist in non-contiguous locations

______b) contiguous allocation of memory in regions whose size cannot be varied

______c) contiguous allocation of memory where region size can be varied dynamically

______d) not capable of multitasking

11. (4 points) There are two approaches to block size in Virtual Memory.

In ______systems block size is equal;

while in ______systems block size is variable.

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