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Chapter 7. Arithmetic Operations and Circuits. 1. 7-1 Binary Arithmetic. Addition When the sum exceeds 1, carry a 1 over to the next-more-significant column. 0 + 0 = 0 carry 0 0 + 1 = 1 carry 0 1 + 0 = 1 carry 0 1 + 1 = 0 carry 1. 5. Binary Arithmetic. Addition
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Chapter 7 Arithmetic Operations and Circuits 1
7-1 Binary Arithmetic • Addition • When the sum exceeds 1, carry a 1 over to the next-more-significant column. • 0 + 0 = 0 carry 0 • 0 + 1 = 1 carry 0 • 1 + 0 = 1 carry 0 • 1 + 1 = 0 carry 1 5
Binary Arithmetic • Addition • General form A0 + B0 = 0 + Cout • Summation symbol () • Carry-out (Cout) 6
Binary Arithmetic • Carry-out is added to the next-more-significant column as a carry-in. 7
Binary Arithmetic • Subtraction • 0 0 = 0 borrow 0 • 0 1 = 1 borrow 1 • 1 0 = 1 borrow 0 • 1 1 = 0 borrow 0 • General form A0B0 = R0 + Bout • Remainder is R0 • Borrow is Bout 8
Binary Arithmetic • Subtraction • When A0 borrows from its left, A0 increases by 210. 10
Binary Arithmetic • Multiplication • Multiply the 20 bit of the multiplier times the multiplicand. • Multiply the 21 bit of the multiplier times the multiplicand. Shift the result one position to the left. • Repeat step 2 for the 22 bit of the multiplier, and for all remaining bits. • Take the sum of the partial products to get the final product. 11
Binary Arithmetic • Multiplication • Very similar to multiplying decimal numbers. 12
Binary Arithmetic • Division • The same as decimal division. • This process is illustrated in Example 7-4. 13
Example 7-4 14
7-2 Two’s-Complement Representation • Both positive and negative numbers can be represented • Binary subtraction is simplified • Groups of eight • Most significant bit (MSB) signifies positive or negative 15
Two’s-Complement Representation • Sign bit • 0 for positive • 1 for negative • Range of positive numbers (8-bit) • 0000 0000 to 0111 1111 (0 to 127) • Maximum positive number: 2N-1-1 • Range of negative numbers (8-bit) • 1111 1111 to 1000 0000 (-1 to -128) • Minimum negative number: -2N-1 16
Decimal-to-Two’s-Complement Conversion • If a number is positive, • the two’s complement number is the true binary equivalent of the decimal number. • If a number is negative: • Complement each bit (one’s complement) • Add 1 to the one’s complement • The sign bit will always end up a 1. 18
Two’s-Complement-to-Decimal Conversion • If the number is positive (sign bit = 0), convert directly • If the number is negative: • Complement the entire two’s-complement number • Add 1 • Do the regular b-to-d conversion to get the decimal numeric value • Result will be a negative number 19
Discussion Point • Convert the following numbers to two’s-complement form: 3510 -3510 • Convert the following two’s-complement number to decimal: 1101 1101 20
7-3 Two’s-Complement Arithmetic • Addition • Regular binary addition • Subtraction • Convert number to be subtracted to a negative two’s-complement number • Regular binary addition • Carry out of the MSB is ignored 21
Discussion Point • Add the following numbers using two’s complement arithmetic: 19 + 27 18 – 7 21 – 13 59 – 96 22