1 Number Systems Lecture 10 Digital Design and Computer Architecture Harris & Harris Morgan Kaufmann / Elsevier, 2007

2 Binary Representations What kind of numbers do you know how to represent using binary representations?

3 Fractional Numbers Fixed-Point Floating-Point

4 Fixed-Point Numbers How do you represent using an 8-bit binary representation with 4 integer bits and 4 fraction bits?

5 Fixed-Point Numbers How do you represent using an 8-bit binary representation with 4 integer bits and 4 fraction bits?

6 Floating-Point Numbers Like scientific notation

7 Floating-Point Numbers How do you represent the value using a 32-bit floating point representation?

8 Floating-Point Numbers

9 Floating-Point Example How do you represent the value using a 32-bit floating point representation?

10 Floating-Point Numbers: Special Cases How do you represent the value 0 using IEEE bit floating-point notation?

11 Floating-Point Numbers: Precision Single-Precision: –32-bit notation –1 sign bit, 8 exponent bits, 23 fraction bits –bias = 127 Double-Precision: –64-bit notation –1 sign bit, 11 exponent bits, 52 fraction bits –bias = 1023

12 Floating-Point Numbers: Rounding Overflow, Underflow Rounding modes: –down –up –toward zero –to nearest

13 Floating-Point Addition 1.Extract exponent and fraction bits 2.Prepend leading 1 to form mantissa 3.Compare exponents 4.Shift smaller mantissa if necessary 5.Add mantissas 6.Normalize mantissa and adjust exponent if necessary 7.Round result 8.Assemble exponent and fraction back into floating- point format

14 Floating-Point Addition: Example Add the following floating-point numbers: Start by representing the numbers in IEEE 754 single- precision floating-point notation.

15 Floating-Point Addition: Example

16 Next Time Sequential Building Blocks Memory Arrays