computer science

# computer science

Télécharger la présentation

## computer science

- - - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - - -
##### Presentation Transcript

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