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York University
Mathematics and Statistics
MATH 1510
John Hofbauer

9 February 2011 CSE-1520R Test #1 [B4] p. 1 of 8 CSE-1520R Test #1 Sur / Last Name: Given / First Name: Student ID: • Instructor: Parke Godfrey • Exam Duration: 45 minutes • Term: Winter 2011 The exam is closed book, closed notes, and no aids such as calculators, cellphones, etc. There are five parts, each with questions. Points for each question are as indicated. Each question is multiple choice, true/false, or fill in the blank, as indicated. For multiple choice, choose the one best answer. There is no negative penalty for a wrong answer. Assume that any number you see is in decimal (base 10), unless it is clear otherwise. The test is out of 50 points. Marking Box 1. /10 2. /10 3. /10 4. /10 5. /10 Total /50 9 February 2011 CSE-1520R Test #1 [B4] p. 2 of 8 1. (10 points) Binary & Number Systems a. (2 points) You see the byte 01101100. You know it represents A. the ASCII character ‘l’ (lowercase ‘L’). B. the natural number 108. C. the negative integer −20 D. the floating point number 3.0. E. There is not enough information to determine. b. (2 points) A natural way to “store” positive and negative (signed) integers in a byte would seem be to use the most significant bit as a sign bit—say, 1 means positive and 0 means negative—and encode the magnitude of the integer in the remaining seven bits in direct binary representation. This is not done, though, because A. we are not allowed to use the most significant bit ever. B. this encodes twice as many positive integers as negative, which is awkward. C. addition would be impossible with this format. D. one would have two different representations. E. zero would have two different representations. c. (4 points) Fill in the blanks. byte format value 8-bit floating point 61 2 00110010 2 11111110 8-bit signed integer, 2’s complement 10100110 hexadecimal d. (2 points) Consider storing signed integers in 16 bits in two’s complement format. The largest integer that can be represented is A. 127 B. 128 C. 32,767 D. 32,768 E. 65,535 F. 65,536 9 February 2011 CSE-1520R Test #1 [B4] p. 3 of 8 2. (10 points) File Systems a. (2 points) The directory that is not contained in any other directory is called A. the source. B. the root directory. C. lonely. D. dangling. E. Such a directory is not possible. b. (4 points) Mark as true or false whether each of the following file types are likely text files (in ASCII or Unicode). .doc .cpp .jpg .wav c. (2 points) An absolute path in the file system to a file is a list of the directory (folder) names—from the topmost directory down to the directory the file is in—followed by the file name. In UNIX or Mac OS, what is the ASCII code in hexadecimal of the separator character used between the directory names in the path? A. 20 B. 21 C. 2E D. 2F E. 5C d. (2 points) What is a named collection of data, used for organizing secondary memory, called? A. a disk B. a directory C. a file D. a byte E. a bit 9 February 2011 CSE-1520R Test #1 [B4] p. 4 of 8 3. (10 points) Data Representation a. (2 points) Consider a 250×400 pixel image in RGB format with 8-bit depth per channel stored in BMP (a direct format with no compression or meta-data). The file size in bytes is A. 1,000 B. 100,000 C. 300,000 D. 314,159 E. 1,000,000 b. (2 points) Recording (analog) audio in a digital format requires A. the MP3 format. B. that one cap the frequency band, meaning it is necessarily lossy. C. stereo, recording in at least two channels. D. that one use decimal, not binary, representation. E. that one record only the deltas between frames. c. (2 points) You encounter an ASCII file with the content Best on the test! (Ignore any linefeed or carriage return characters that might be in the file.) What is the file’s size in bytes? A. 1 B. 14 C. 17 D. 28 E. 34 d. (4 points) Dr. Dogfurry gets an image file mugshot.bmp (284 × 207 pixels). BMP is a direct format with no compression or meta-data. He uses an image converter application to take the same image to put it into the JPG, PNG, and TXT formats (mugshot.jpg, mugshot.png, and mugshot.txt, respectively). JPG does a decent, lossy compression. PNG does moderate, lossless compression. TXT represents the RGB values in ASCII for each pixel on a separate line, for easy reading. (E.g., 252,35: ( 40, 39, 37)#2827
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