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computer science

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  1. CSCI 1001 overview of computer science REPRESENTING DATA I

  2. What do each of these mean: VII 7 How do computers represent data?

  3. Review: Decimal What does the digit sequence 563 mean? 5×102 + 6×101 + 3×100

  4. bit: a value that is either 0 or 1 string: a sequence of bits byte: a string of 8 bits

  5. Binary A bit string can represent a number: 110 = 1×22 + 1×21 + 0×20 A byte has the place values: What is the smallest possible byte? the largest?

  6. Input: a positive integer N • Find the largest k so that 2k ≤ N • for each power_of_2 ∈ {2k,2k-1,…,1}: • if N ≥ power_of_2 then: • set N = N - power_of_2 and output 1 • else: • output 0 • 3. stop. • setp = 1 and k = 0 • whilep ≤ N/2: • set p = p×2 and k=k+1 PRACTICE: 11011100, 93, 42

  7. Hexadecimal Base 16: 0,1,2,…,9,A,B,C,D,E,F 0x37 • = 5510 0x1A • = 2610 0xC2 • = 19410 How many bits for a hex digit? 4 (a nibble)

  8. Hex Binary Decimal 0x2C 10100011 217

  9. ascii 1 Letter = One byte “MINNESOTA” ⇒ 0x4D494E4E45534F5441 Moby Dick = 1,255,836 bytes

  10. UNICODE: One letter = 8 or 16 bits

  11. 1 1 1 1011 0111 + 1 1 0 0 0

  12. http://cs1001.us/ Please read Chapter 4.2.2 for Wednesday’s lecture.