Unit 1 quiz
Ten questions with a think-time countdown and explained answers.
Transcript
Ten quick questions on data representation. Listen, think, then check your answer.
Question one. What is the hexadecimal value of the binary number one zero one zero one one one one? A, A F. B, F A. Or C, nine E.
The answer is A. Split into nibbles: one zero one zero is A, and one one one one is F.
Question two. What is forty five as an eight bit binary number? A, zero zero one one zero one zero one. B, zero zero one zero one one zero one. Or C, zero zero one zero one zero one one.
The answer is B. Forty five is thirty two, plus eight, plus four, plus one.
Question three. What is zero zero one one zero one one zero, plus zero zero zero one one zero one one? A, zero one zero zero one zero zero one. B, zero one zero one zero zero zero one. Or C, zero one zero one zero zero one one.
The answer is B. Fifty four plus twenty seven is eighty one, which is zero one zero one zero zero zero one.
Question four. Two eight bit numbers are added, and the answer needs a ninth bit. What is this called? A, a parity error. B, overflow. Or C, compression.
The answer is B, overflow. The register only holds eight bits, so the extra carry is lost.
Question five. What is the effect of a logical shift left by three places? A, multiplies by three. B, multiplies by eight. Or C, divides by eight.
The answer is B. Each place to the left multiplies by two, and two times two times two is eight.
Question six. In eight bit two's complement, what is one one one one one one one zero? A, minus two. B, two hundred and fifty four. Or C, minus one hundred and twenty six.
The answer is A, minus two. Minus one twenty eight, plus one hundred and twenty six, is minus two.
Question seven. What is the main advantage of Unicode over ASCII? A, smaller files. B, many more characters and languages. Or C, simpler codes.
The answer is B. Unicode uses more bits per character, so it can represent every language and symbol, at the cost of bigger files.
Question eight. A sixteen by sixteen image has a colour depth of four bits. What is its size in bits? A, two hundred and fifty six. B, one thousand and twenty four. Or C, four thousand and ninety six.
The answer is B. Sixteen times sixteen is two hundred and fifty six pixels, times four bits, is one thousand and twenty four bits.
Question nine. A sound is sampled one hundred times a second, with eight bits per sample, for ten seconds. How many bytes is the file? A, one thousand. B, eight thousand. Or C, eighty.
The answer is A. One hundred times eight times ten is eight thousand bits, and dividing by eight gives one thousand bytes.
Question ten. Which type of compression lets you rebuild the original file exactly? A, lossy. Or B, lossless.
The answer is B, lossless. Lossy compression removes data for good, as in J P E G and M P three.
That is the end of the quiz. Review any topic you missed. Good luck with your test.
More in this series
2:41Denary, binary and hexadecimal
Place values, converting denary to binary and back, and why hex is used for bytes.
2:30Binary addition, overflow and shifts
Adding binary numbers with carries, overflow when a ninth bit is needed, and logical shifts as multiply and divide.
2:12Two's complement
Negative numbers in binary: the -128 place value, invert and add one, and reading a signed byte.
1:45Text: ASCII and Unicode
Character sets give every character a code. ASCII's 128 codes, Unicode's millions, and the storage trade-off.
1:27Images
Pixels, resolution, colour depth, image file size and metadata.
1:38Sound
Sampling an analogue wave: sample rate, bit depth, quality against file size.
1:50Storage units and file sizes
Bit to pebibyte in steps of 1024, and calculating image and sound file sizes.
1:58Compression
Why files are compressed, lossy against lossless, and run-length encoding step by step.