2. Representation of Integers HKCE Computer Studies Education Department 2000

3. Sign-and-magnitude 符號數值表示法 1 1 0 0 1 1 0 1 Sign 0 Pos 1 Neg Magnitude

4. 3-bit example 011 010 001 000 +3+2+1+0+3+2+1+0 111 110 101 100 -3-2-1-0-3-2-1-0

5. 011 010 001 000 100 101 110 111 +3 +2 +1 -2 -3 +0 or -0 ?

6. Two’s Complement 二進制補碼 counter on cassette recorder … 001 000 111... Play Reverse

7. 011 010 001 000 100 101 110 111 Negative Positive +3 +2 +1 0 -2 -3 -4

8. 2’s Complement of 1. Positive Number 2. Binary Format 3. Interchange 0’s and 1’s 4. Add 1 to code 25 00011001 11100110 11100111 - 25

9. 2’s Complement of 1. Positive Number 2. Binary Format 3. Interchange 0’s and 1’s 4. Add 1 to code 103 01100111 10011000 10011001 - 103 Ex.

10. 2’s Complement of 1. Positive Number 2. Binary Format 3. Interchange 0’s and 1’s 4. Add 1 to code 149 10010101 01101010 01101011 = +107 Why? - 149 Ex.

11. What is the decimal form of the 2’s complement value, 10101010 ?

12. Home Assignment Reply the email on home assignment. Visit the web pages in the email for the preparation of the next lesson.