RMIT School of Computer Science and Information Technology

Introduction to Computer Systems Practice Examination

Time Allowed: 2 hours, plus 15 minutes initial reading time

INSTRUCTIONS – PLEASE READ CAREFULLY

The exam is closed-book; no reference materials are allowed other than those provided in this examination document.

You may make reasonable assumptions; if so, state these clearly with your answer.

All questions are to be attempted. You may do them in any order.

This exam contributes 50% of your overall assessment for this subject. You must achieve at least 25 marks on this examination to pass the course. For the multiple choice questions, select only one response you consider most correct.

This examination consists of 6 pages (including this page) and 18 questions as follows:

10 multiple choice questions 10 x 1 mark each = 10 marks

5 short answer questions 5 x 4 marks each = 20 marks

3 applied questions 7 + 6 + 7 marks = 20 marks

TOTAL MARKS ON THIS EXAMINATION = 50 marks

Part A: Multiple Choice Each multiple choice question has only one correct answer. 1. What is a difference between registers and memory?

a) Registers cannot store any data.

b) Registers are used for storing data about the instruction being executed.

c) Data is fetched from the registers, into main memory for execution.

d) Registers only hold references to memory addresses.

2. What is the “SMART” system, for mass storage?

a) It prevents file fragmentation through intelligent organisation.

b) It monitors various indicators for device reliability/imminent failure.

c) It is a predictive caching system that works with the operating system.

d) It monitors and optimises system performance.

3. Which logic gates can be built using NAND gates?

a) AND

b) OR

c) NOT

d) All of the above

4. What is a guaranteed solution to Wi-fi signal spectrum congestion?

a) Changing the wi-fi access point to use a different channel.

b) Increasing the transmit power, and/or fitting better antennas to the access point.

c) Contacting the ACMA, and reporting it for investigation.

d) There is no guaranteed solution.

5. What is the most power a standards-compliant USB 2.0 port can deliver to a device?

a) 0.5 Watts

b) 2.5 Watts

c) 4.5 Watts

d) 10 Watts

6. Which of the following is most likely to crash an entire operating system?

a) End-user applications

b) The kernel

c) Device drivers

d) A virtual machine that has crashed.

7. Is the following Boolean algebra expression correct?

-a + b . c + d = -(a + b) . (c + d)

a) Yes

b) No

c) It depends on the values of a, b, c and d.

8. What is not a method of recording data onto regions of a rotating disc?

a) Manipulating the magnetic properties of a magnetic disc.

b) Pressing ‘pits’ onto a plastic optical disc.

c) Using a laser to etch ‘pits’ onto a plastic disc.

d) Using a laser to manipulate chemical properties of a plastic disc.

9. Which of the following were limitations of Parallel ATA?

a) Data transfers involved the CPU.

b) Interface speeds couldn’t rise above 100MB/sec.

c) The cables connecting devices had to be rather short.

d) Both (a) and (b).

e) Both (b) and (c).

10. Why were “small outline” memory modules (SO-DIMMs) developed?

a) Standard modules were too large for portable computers.

b) So that memory of one standard (e.g. DDR2) would not physically fit into a socket for another standard (e.g. DDR3).

c) The performance characteristic of standard DIMMs were not necessary for portable systems.

d) Both (a) and (c).

Part B: Short Answer Answers to these questions are expected to be between three and five sentences long.

11. Briefly define what is meant by “gate leakage” in semiconductors, and explain the real-world effect of this in a computer system. What design choices influence the amount of gate leakage?

12. Perform the following base conversions, showing all working:

a) 11001 (base 2), to base 10

b) 2E (base 16), to base 10

13. Identify, and briefly explain the two major contributors to latency for magnetic hard disks.

14. A computer is connected to a wireless network. The wireless network adapter supports dual-band 802.11n, but the computer is only connected at 36 Mbit/sec.

a) What are two reasons why the computer not be able to connect to the wireless network at a higher speed?

b) The user starts transferring a file, but it only transfers at 1.3 MB/sec. What might be causing the transfer speed to be much lower than the stated wireless connection speed?

15. Many modern computer system have many processor cores in the CPU. Answer the following questions about multi-core system design:

a) Why doesn’t doubling the number of processor cores double the performance of the system?

b) What effect does a multi-core system design have on multitasking? Why?

Part C: Applied Questions 17. An old computer is currently assembled as per the following block diagram:

a) What is the advantage of having the hard drives and DVD drive connected the way they

are, on separate Parallel ATA channels?

b) Transfers often occur between the two hard drives – and as such, someone has suggested putting the hard drives on separate Parallel ATA buses by moving one to the same bus as the DVD drive.

i. Why might this increase throughput for this type of workload?

ii. In what situation might the moved hard disk’s performance be affected?

iii. Which hard disk would you suggest gets moved to the same Parallel ATA bus as the DVD drive? Why?

c) If a USB device connected to the USB 2.0 card is transferring data at 30 MB/sec, what is the theoretical maximum performance from the Gigabit Ethernet controller?

CPUPentium 4 2.8GHz 800MHz FSB

NorthbridgeMemory

2GB RAM DDR2-800

GraphicsGraphics Card

AGP 8x

Southbridge

PCI Card Gigabit Ethernet

Controller

PATA (UDMA133)

Hard Disk 200GB

UDMA66

DVD DriveUDMA66

PCI Bus

PCI Card USB 2.0

Card

PATA(UDMA133)

Hard Disk 750GB

UDMA133

unused slot

unused slot

18. In the system as described in question 17, consider the feasibility and upgrade potential along the following lines:

i. Is upgrading this component feasible?

ii. How can the upgrade be facilitated?

iii. What potential bottlenecks might occur from this?

Consider these three points for the following potential upgrades:

a) Upgrading the USB ports to version 3.0.

b) Adding a Serial ATA solid-state disk.

19. Consider the following logic diagram:

a) Identify the three gates being used in the diagram.

b) Complete a truth table that shows the output (X) for inputs (W, P and D).

c) Write the logic expression that is equivalent to the diagram. (It need not be simplified.)

– END OF EXAMINATION QUESTIONS –

A page of reference materials follow.

X

Reference Material

Note: M = Mega, G = Giga, B = byte, b = bit, /sec = per second Interface Performance Chart (Theoretical Peak) Processor FSB

Pentium 4, 533MHz 4.3 GB/sec

Pentium 4, 800MHz 6.4 GB/sec

Pentium 4, 1066MHz 8.5 GB/sec

Memory

SDRAM PC66 0.5 GB/sec

SDRAM PC100 0.8 GB/sec

SDRAM PC133 1.1 GB/sec

DDR 266 2.1 GB/sec

DDR 333 2.7 GB/sec

DDR 400 3.2 GB/sec

DDR2-400 3.2 GB/sec

DDR2-533 4.2 GB/sec

DDR2-800 6.4 GB/sec

DDR3-1066 8.5 GB/sec

DDR3-1333 10.7 GB/sec

DDR3-1600 12.8 GB/sec

Internal Expansion

PCI Bus 133 MB/sec

AGP 1x 266 MB/sec

AGP 2x 533 MB/sec

AGP 4x 1.06 GB/sec

AGP 8x 2.13 GB/sec

PCI Express 1.0 Lane 250 MB/sec

PCI Express 2.0 Lane 500 MB/sec

External Ports

USB Low Speed 1 Mb/sec

USB Full Speed 11 Mb/sec

USB High Speed 480 Mb/sec

USB Super Speed 5 Gb/sec

FireWire 400 400 Mb/sec

FireWire 800 800 Mb/sec

Mass Storage

Ultra DMA 33 33 MB/sec

Ultra DMA 66 66 MB/sec

Ultra DMA 100 100 MB/sec

Ultra DMA 133 133 MB/sec

Serial ATA 1.0 150 MB/sec

Serial ATA 2.0 300 MB/sec

Serial ATA 3.0 600 MB/sec

Networks

100BASE-T 100 Mb/sec

Gigabit Ethernet 1 Gb/sec

802.11a 54 Mb/sec

802.11b 11 Mb/sec

801.11g 54 Mb/sec

802.11n 150 Mb/sec

802.11n Dual Band 300 Mb/sec

– END OF DOCUMENT –