Fiber Optic Interconnections Within Computer Systems - Multiple Choice Questions

These multiple choice questions are designed to test your knowledge Fiber Optics Interconnections. Should you encounter any difficulties on answering these questions, feel free to refer back to the articles prepared by Shahrin Imran & Mugunthan Sandrakasan.

Each question is rated as shown below:


Easy .... Hard

Q1. Light is confined within the core of a simple optical fiber by

    A. refraction.
    B. total internal reflection at the outer edge of the cladding.
    C. total internal reflection at the core cladding boundary.
    D. reflection from the fiber's plastic coating.
Answer



Q2. What makes optical fibers immune to EMI?

    A. They transmit signals in as light rather than electric current.
    B. They are too small for magnetic fields to introduce current in them.
    C. Magnetic fields cannot penetrate the glass of the fiber.
    D. They are readily sheilded by outer conductors in cable.
Answer



Q3. Which of the following is not a reason to use fiber-optic cables for point to point data transmission?

    A. Need to assure data security.
    B. Avoidance of ground loops.
    C. Data-transfer rates too low to use metal cables.
    D. Elimination of spark hazards.
Answer



Q4. Which of the following describes a technique to achieve fault tolerance in optical networks with minimum costs?

    A. Bypassing active elements.
    B. Avoid the usage of star couplers..
    C. Duplication of system properties.
    D. Topological reconfiguration.
Answer



Q5. When would optical fibers be used in an Ethernet-type LAN?

    A. Never, the standard calls for coaxial cable.
    B. To extend transmission distance to reach remote terminals.
    C. Routinely, the standard allows for optical fiber.
    D. When transmission speeds exeed 50 Mbit/s.
Answer



Q6. What are the advantages of using parallel optical fiber interconnections within board-to-board or frame-to-frame connections in computer systems?

    A. No bandwidth limit.
    B. Space saving.
    C. Avoids electrical crosstalk.
    D. All of the above.
Answer



Q7. What technological progress has allowed the full usage of fiber optics within parallel computer architechture?

    I. There are compilers and programming that recognise and exploit parallelism.


    II. Widely tunable semiconductor lasers allow maultiple wavelength system.


    III. Newly designed operating system for parallel processing.


    IV. Migration of architectural features previously found on mainframes onto single-chip microprocessors.

    A. I and III only.
    B. II, III and IV only.
    C. I, II and IV only.
    D. I, II, III and IV.
Answer



Q8.Which of the following is NOT a reason to use flexible optical circuits?

    A. Low loss distribution.
    B. Protection of fiber.
    C. Small size.
    D. Compact and bend easily.
Answer



Q9. The Fiber Distributed Data Interface (FDDI) standard calls for nodes to be:

    A. attached to a data bus in the form of a transmissive star coupler.
    B. attached to a pair of fiber rings carrying signals in opposite directions.
    C. attached to a network of star couplers that detect collisions and transmit only one signal to the next level.
    D. attached to fibers by passive T couplers.
Answer



Q10.The type of light source and fiber chosen for FDDI networks are:

    A. single-mode fiber and 1550-nm lasers.
    B. single-mode fiber and 1300-nm lasers.
    C. multi-mode fiber and 1300-nm lasers.
    D. multi-mode fiber and 1300-nm LEDs.
Answer



Q11. Which of the following happen to be the limitations of optical fiber ?

    I. The architecture of their couplers.


    II. Costs of implementing them.


    III. Modification of the software and hardware on existing systems.


    IV. The difficulty of installing the cables.

    A. II and IV only.
    B. I,II and III only.
    C. I,III and IV only.
    D. I,II,III and IV.
Answer



Q12.Speeds of laboratory fiber optic Local Area Networks are now in the range of

    A. 1 Mbits/s.
    B. 10 Mbits/s.
    C. gigabits per second.
    D. hundreds of megabits per second.
Answer



Q13.Which of the following is NOT true about digital signals used in fiber optic transmissions ?

    A. It's more compatible with people.
    B. It's much simpler to design a circuit to detect the signal level.
    C. There's less distortion in the signals as it goes through a system.
    D. Isn't difficult to differentiate the on from off state even if the signal is not reproduced exactly.
Answer



Q14. What method allows large number of independent, selectable channels to exist on a single fiber?

    A. Frequency Division Multiplexing.
    B. Time Division Multiplexing.
    C. Analague Modulation.
    D. Phase Modulation.
Answer



Q15. Which of the following statement about interconnection networks is true?

    A. The number of channels on a single fiber that can transmit data simultaneously refers to the degree of simultaneity.
    B. Degree is the number of channels on a single fiber.
    C. Point-to-point communication connections are called switches.
    D. Diameter is the number of links in the largest path between any two nodes.
Answer



Q16. What type of optical fiber would best be used in the Multiple Channel Architechture (MCA)?

    A. Refractive-Index.
    B. Step-Index.
    C. Graded-Index.
    D. None of the above.
Answer



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Copyright © 1997 Shahrin Imran (si1@doc.ic.ac.uk) & Mugunthan Sandrakasan (sm27@doc.ic.ac.uk)



References:

J.W. Goodman,
"Optical Connections for VSLI systems,"
IEEE, 1989.
Edward E.E. Frietman,
"Optical Interconnections in a Multicomputer Environment",
SPIE, 1991.
P. Healey and D.W. Smith,
"Multidimensional Optical Interconnection Networks",
Proc. SPIE, Digital Optical Computing, 1992.
L. Melchior, J.-R Kropp,
"A High Density Optical Backplane Connector",
1996 Electronic Components and Technology Conference.
Tom S. Wailes and David G. Meyer
"A New Optical Interconnection Strategy For Massively Parallel Computers"
Journal Of Lightwave Technology, vol.9, No.12, December 1991.
Article 1 and Article 2 by Mugunthan Sandrakasan.
Article 1 and Article 2 by Shahrin Imran.