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MODD / Mr. Hansen |
Name:
_________________________ |
Test #1
A calculator is permitted. Do not spend too much time
on any single problem. Clues to some problems that you cannot solve initially
may be found elsewhere in the test.
Part I: Fill-Ins and Short Essays (6 pts. each).
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1. |
The word digital in MODD should be explained
not as meaning “numeric” but rather as meaning _____________________________ . Why is the word “numeric” not really the best word to
use? |
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2. |
Note: In this problem, I
will not tell you whether the word “file” is meant to refer to a computer
file or to a hard copy printout stored in a filing cabinet. Is a novel stored
as a text file (no numbers) in digital or analog format? ________ How do you
know? |
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__________________________________________________________________ |
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__________________________________________________________________ |
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__________________________________________________________________ |
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3. |
Sketch a circuit diagram
that captures this logic: ~(A · B) + (B · C). For a bonus
point, use exactly one NAND gate. If you have forgotten what some of the
symbols mean, or if you have forgotten some of your circuit diagram symbols,
you can buy some hints. |
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4. |
State Moore’s law. |
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__________________________________________________________________ |
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__________________________________________________________________ |
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5. |
If Moore’s law continues to
hold for the next 20 years, how many more doublings of computer power will
occur between now and then? _____ This represents a growth factor of 2 to
what power? _____ Use our estimating rule to round this growth factor to the
nearest power of 10. ___________ |
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6. |
Continuing with the ideas
of #5, if today’s PCs run at, say, 2.8 GHz, then approximately how fast will
they be in the year 2026? (Bonus point for using the most appropriate
abbreviation in your answer.) |
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Part II: Multiple Choice and Essay (4 pts. each).
There are no additional penalty points for wrong guesses.
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7. |
The prefix “mega”
(abbreviated M) means . . . |
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(A) million |
(D) 1,073,741,824 |
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8. |
Hexadecimal (“hex”)
notation is based on powers of . . . |
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(A) 3 |
(D) 10 |
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9. |
If an audio signal is sampled
using 16-bit samples, as is the case for CD-quality audio, then each sample
can indicate one of how many possible amplitude values? |
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(A) 28 |
(D) 162 |
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10. |
Stereo CD-quality audio,
sampled at 44,1 KHz, requires how many samples per
second? |
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(A) 44.1 |
(D) 88,200, since there are
two channels |
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11. |
The data requirement for CD-quality
digital audio is about 172 KB per second. Why is the answer not 176.4
KB/sec., as you might expect by doing the arithmetic and working from problem
#10? (Reminder: 16 bits equals 2
bytes.) |
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(A) one KB is actually 1024
bytes, not 1000 |
(D) CDs are not digital |
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12. |
Use the fact given in #11 (172
KB/sec.) to determine how much uncompressed music will fit on a 660 MB CD. Note: MP3 is a compressed format and
can store much more. Give your answer for uncompressed
digital music. |
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(A) about 10 minutes |
(D) about 6 hours |
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13. |
As noted above, 16-bit
samples are standard for audio CDs. What would be the signal-to-noise ratio
for 12-bit samples (in dBV)? |
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(A) 12 (B) 24 (C) 48 |
(D) 72 (E) 96 |
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14. |
Human hearing includes
frequencies up to about 20 KHz. According to Nyquist’s
Theorem, what is the minimum sampling rate needed in order to represent these
frequencies faithfully without aliasing errors? |
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(A) 5 KHz (B) 10 KHz (C) 20 KHz |
(D) 30 KHz (E) 40 KHz |
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15. |
Convert a power ratio of
80,000:1 into decibels. |
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(A) 9 dB (B) 90 dB (C) 39 dB |
(D) 49 dB (E) 59 dB |
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16. |
An audio engineer says,
“Hey, bring that up 6 dB, would you?” What she means is that you should . . . |
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(A) double the power (B) triple the power (C) quadruple the power |
(D) quintuple the power (E) sextuple the power |
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17. |
What causes the “jaggies” you often see on photos in The Independent or
The Saint Albans News? |
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(A) insufficient bit depth (B) undersampling (C) bad software |
(D) incompetent printing (E) censorship |
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18. |
Posterization (i.e., large patches of color information showing
no gradation whatsoever, just solid blobs all exactly the same color) is a
phenomenon caused by . . . |
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(A) insufficient bit depth (B) undersampling (C) bad software |
(D) incompetent printing (E) censorship |
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19-20. |
Prove that ~(A · B) Û (~A + ~B) by means of a truth table. |
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21-22. |
Explain how it is that on
TV commercials showing cars in motion, the turning wheels may appear to be
rotating in the wrong direction. |
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