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C o m p u t e r S c i e n c e : A n O v e r v i e w 1 2 t h E d i t i o n
B y G l e n n B r o o k s h e a r , D e n n i s B r y l o w Complete Test bank, All Chapters are included. Test Bank —Chapter One (Data Representation) Multiple Choice Questions 1. Which of the following Boolean operations produces the output 1 for the fewest number of input patterns? A. AND B. OR C. XOR ANSWER: A 2. Which of the following best describes the NOR operation? A. An XOR followed by a NOT B. An OR followed by a NOT C. A NOT followed by an OR C. An AND followed by a NOT ANSWER: B 3. Which of the following bit patterns cannot be expressed in hexadecimal n otation? A. 11111111 B. 1001 C. 110011 D. 100000000001 ANSWER: C 4. Which of the following is the binary representation of 6 5/8? A. 110.11 B. 10.011 C. 110.101 D. 100.101 ANSWER: C 5. Which of the following bit patterns represents the value 9 in two ’s complement notation? A. 00011010 B. 11111011 C. 00001001 D. 11111011 ANSWER: C 6. Which of the following bit patterns represents the value - 9 in two ’s complement notation? A. 00011010 B. 111110111 C. 10001001 D. 11111011 ANSWER: B 7. What is the result of the following addition problem (using two ’s complement notation)? 00001111 + 10101010 A. 011000101 B. 10111001 C. 01010101 D. 10110101 ANSWER: B 8. What is the result of the following subtraction problem (using tw o’s complement notation)? 00001111 - 10101010 A. 011000101 B. 10111001 C. 01010101 D. 10110101 ANSWER: A 9. In which of the following addition problems (using two ’s complement notation) does an overflow error occur? A. 0011 B. 1100 C. 1100 D. 0100 + 1010 + 0100 + 1100 + 0100 ANSWER: D 10. Which of the following representations in two ’s complement notation represents the largest value? A. 00000010 B. 11110000 C. 00000001 D. 11111111 ANSWER: A 11. Which of the following representations in two ’s complement notation represents the smallest value? A. 00000010 B. 11110000 C. 00000001 D. 11111111 ANSWER: D 12. Which of the following bit patterns (represented in hexadecimal notation) represents a negative number in two ’s complement notation? A. 3F B. 55 C. A6 D. 7E ANSWER: C 13. Which of the following bit patterns (represented in hexadecimal notation) represents a positive number in two ’s complement notation? A. 9F B. F7 C. A8 D. 7E ANSWER: D 14. What value is represented by the bit pattern 01011100 when interpreted u sing floating-point format in which the most significant bit is the sign bit, the next three bits represent the expo nent field in excess notation, and the last four bits represent the mantissa? A. -1 1/2 B. 1 1/2 C. -3/8 D. 3/8 ANSWER: B 15. Which of the following values cannot be stored accurately using a floating -point format in which the most significant bit is the sign bit, the next three bits represent the exponent field in excess notation, and the last four bits represent the mantissa? A. 2 1/2 B. 3/16 C. 7 D. 6 1/4 ANSWER: D 16. Which of the following bit-patterns represents the smallest value using the floating-point format in which the most significant bit is the sign bit, the next three bits represent the exp onent field in excess notation, and the last four bits represent the mantissa? A. 01001000 B. 01011000 C. 00101000 D. 01111000 ANSWER: C 17. Which of the following data storage systems provides the most efficient ran dom access to individual data items? A. Main memory B. Magnetic disk C. CDs/DVDs D. Flash drives ANSWER: A 18. Which of the following storage systems is best suited for storing and retrieving long strings of data that are processed in their sequential order? A. Main memory B. Magnetic disk C. CDs/DVDs ANSWER: C 19. Which of the following mass storage system does not require physical motion ? A. Magnetic tape B. Magnetic disk C. CDs/DVDs D. Flash drives ANSWER: D 20. Assuming that each of the following bit patterns originally had even parity, which one contains an error? A. 100110100 B. 110000011 C. 010011000 D. 100011001 ANSWER: C 21. How many errors per pattern could be corrected when using an erro r-correcting code in which any two code patterns differ by a Hamming distance of 8? A. 3 B. 4 C. 5 D. 6 ANSWER: A 22. Which of the following is a possible LZW compression of the message “xyz xyz xyz ”? A. 1234 B. 1234545 C. 232 D. 12 ANSWER: B 23. Which of the following systems is least efficient when encoding numeric values? A. Two ’s complement notation B. Excess notation C. ASCII D. Floating-point notation ANSWER: C 24. Which of the following is a means of encoding music? A. ASCII B. MIDI C. JPEG D. GIF ANSWER: B 25. Which of the following provides a compress ed representation of an image by limiting the number of different pixel colors to 256, thereby enabling each pixel in an image to be represented by a single byte whose value indicates which of a palette of entries represents the pixel ’s color? A. ASCII B. MPEG C. JPEG D. GIF ANSWER: D Fill-in-the-blank/Short-answer Questions 1. A computer ’s main memory consists of numerous memory cells, each of wh ich contains ________ bits. Each memory cell is identified by a numeric value called the cell ’s _________. ANSWER: eight, address 2. Represent the bit pattern 1111010010011011 in hexadecimal notation. _________ ANSWER: F49B 3. A7DF is the hexadecimal representation for what bit pattern? __________ __ ANSWER: 1010 0111 1101 1111 4. How many different bit patterns can be formed if each must consist o f exactly 6 bits? ____________ ANSWER: 64 5. How many bits are needed to represent 1024 different bit patterns? ____________ ANSWER: 10 6. Translate each of the following binary representations into its equivalent b ase ten representation. A. 1100 __________ B. 10.011 __________ C. 0.01 __________ D. 10001 __________ ANSWER: A. 12 B. 2 3/8 C. 1/4 D. 17 7. Rewrite each of the following values (represented in base ten notation) in binary notation. A. 7 __________ B. 23 __________ C. 2 1/4 __________ D. 5/8 __________ ANSWER: A. 111 B. 10111 C. 10.01 D. 0.101 8. If the patterns 101.11 and 1.011 represent values in binary notation, what is the binary representation of their sum? ____________ ANSWER: 111.001 9. Using a two ’s complement notation system in which each value is represented by a pattern of six bits, represent the value 5. ____________ ANSWER: 000101 10. Using a two ’s complement notation system in which each value is represented by a pat tern of six bits, represent the value -5. ____________ ANSWER: 111011 11. What is the largest positive integer that can be represented in a two ’s complement system in which each value is represented by eight bits? ____________ ANSWER: 127 (represented by 01111111) 12. What is the smallest negative integer that can be represented in a two ’s complement system in which each value is represented by eight bits? ____________ ANSWER: -128 (represented by 1 0000000 ) 13. In a two ’s complement system, what value is represented by the pattern 1111111111 1111001? ____________ ANSWER: -7 14. When using two ’s complement notation, what bit pattern represents the negation of 01001010? ____________ ANSWER: 10110110 15. What value is represented by each of the following patterns in excess n otation? A. 10000 ____ B. 0110 ____ C. 1100 ____ ANSWER: A. 0, B. -2, C. 4 16. Using an 8- bit floating-point format in which the most significant bit is the sign bit, the next t hree bits represent the exponent field in excess notation, and the last four bits represent the mantissa, write the bit pattern that represents the value 1 3/4. (Use normalized form.) ____________ ANSWER: 01011110 17. What is the largest value that can be represented in a floating-point system in which each value is encoded by a byte whose most significant bit is the sign bit, the next three bits represent the exponent field in excess notation, and the last four bits represent the mantissa? ____________ ANSWER: 7 1/2 (represented as 01111111) 18. Which of the following addition problems cannot be solved accurately when using a floating-point system in which each value is encoded by a byte whose most significan t bit is the sign bit, the next three bits represent the exponent field in excess notation, and the last four bits represent th e mantissa? A. 2 1/2 + 1 3/8 B. 3 1/2 + 4 1/2 C. 7 + 3/4 ____________ ANSWER: A, B, and C 19. The following is an error-correcting code in which any two patter ns differ by a Hamming distance of at least three. Symbol Representation A 000000 B 001111 C 010011 D 011100 E 100110 F 101001 G 110101 H 111010 Decode each of the following patterns 010011 ________ 101010 ________ 011000 ________ 101101 _______ ANSWER: C, H, D, F 20. How many errors in a single code pattern could be corrected when usi ng an error-correcting code in which each code pattern is a Hamming distance of at least seven from any o ther code pattern? ____________ ANSWER: 3 21. The following is a message that was originally encoded so that each patter n had odd parity. Circle the patterns in which an error has definitely occurred. 101110101 111110000 100010010 000000000 111111111 010001000 100111101 ______________________________________ ANSWER: First, fourth, sixth, and seventh 22. Data compression techniques apply various principles to reduce the size of d ata. One, called _______________________, avoids repeating long strings of the same data item. Another, called _______________________, encodes the difference between consecutiv e blocks of data rather than encoding each block in its entirety. Still another, called _____________ ____________, uses short bit patterns to encode frequently occurring items and longer patterns to encode less frequent items. ANSWER: Run-length encoding, relative encoding, and frequency-depend ent encoding. Vocabulary (Matching) Questions The following is a list of terms from the chapter along with descriptive phr ases that can be used to produce questions (depending on the topics covered in your course) in which the students are ask to match phrases and terms. An example would be a question of the form, “In the blank next to each phrase, write the term from the following list that is best described by the phrase. ” Term Descriptive Phrase bit Binary digit Boolean operation AND, OR, XOR, NOT address A numeric value used to identify a memory cell hexadecimal notation An efficient way of representing bit patterns track A circle on the surface of disk platter on which data is written/rea d sector A segment of a track in a mass storage system cylinder A set of tracks at a given position of the read/write head s seek time The time required to move the read/write heads from one tra ck to another latency time The average amount of time required for the desired data to rotate around to the read/write head transfer rate The rate at which data can be written to or read from a devic e zoned-bit recording A means of increasing the storage capacity of a magnetic disk system ISO An international organization for establishing standards ANSI A major standardization organization within the United States ASCII A system developed by the American Standards Institute for encod ing text. flip-flop A digital circuit capable of holding a single digit two’s complement notation A means of encoding whole numbers floating-point notation A means of encoding numeric values that may involve fractions truncation An error that may occur when using floating-point no tation pixel A small part of an image GIF A means of compressing an image file by restricting the nu mber of colors available JPEG A means of compressing images by blurring the boundar ies between different colors while maintaining all brightness information Unicode A means of encoding text in which each symbol is represented by 21 bits which may be encoded in UTF-8, UTF-16, or UTF-32 formats. SD card An application of flash technology Flash memory A mass storage device that traps electrons in tiny chambers of silicon dioxide LZW An example of adaptive dictionary encoding MIDI A means of encoding music in terms of notes and instruments rather than actual audio VLSI A means of constructing complex circuitry in a very small space. General Format Questions 1. Describe how a computer can produce an incorrect answer when perfo rming numerical computations even though it has not malfunctioned. ANSWER: Most students will probably refer to overflow and truncation errors. 2. Describe how the concept of Hamming distance is used to produce an er ror-correcting code. ANSWER: By designing a code in which each pattern has a Hamming distance of n from any other pattern, patterns with fewer than n/2 errors can be corrected by replacing them with the code pattern that is closest. 3. a. What is the output of the circuit below? b. In general, how does the three-bit input pattern across the top of the d iagram relate to the circuit ’s output? ANSWER: a. 0 b. The output is 0 if the input parity is odd; the output is 1 if the input parity is even. 4. If the input and output bit patterns in the circuit below are interpreted as binary representations of numeric values, what operation does the circuit perform? ANSWER: The circuit subtracts one (except for the case of the input being 000) . 5. Explain why such terms as kilo, mega, and giga have acquired doub le meanings. ANSWER: The prefixes kilo, mega, and giga are used traditionally to refer to units measured in powers of thousand. However, in reference to memory capacities the se prefix es are used to reference units that are powers of two. For example, one kilobyte is 210, which is 1024 bytes. 6. Convert the following addition problem into two ’s complement notation (using four bits per value), perform the addition, convert the answer back into base ten notation, and exp lain the results. 6 + 3 ANSWER: In two ’s complement notation the problem is to add 0110 and 0011. The sum i s 1001 which translates to -7. This answer is incorrect due to overflow. 7. Under what condition is each of the following data compression techniqu es most effective? a. Run-length encoding b. Relative encoding ANSWER: a. Compresses most when data consists of long strings of t he same entry. b. Compresses most when each block of data differs little from the prev ious block. 8. What is frequency-dependent encoding? ANSWER: Frequency-dependent encoding is an encoding system that uses sh ort bit patterns to represent data items that occur most often and longer patterns to represent less frequen tly occurring items. The result is that entire blocks of data can be represented in less space than would be requ ired if each data item were represented by the same size bit pattern. 9. Construct the entire two ’s complement scale in which each value is represented by three bits. ANSWER: 3 011 2 010 1 001 0 000 -1 111
