Subtraction of Unsigned Numbers-2

Since we are dealing with unsigned numbers, there is really no way to get an unsigned result for the second example. When working with paper and pencil, we recognize that the answer must be changed to a signed negative number. When subtracting with complements, the negative answer is recognized by the absence of the end carry and the complemented result.

Subtraction with complements is done with binary numbers in a similar manner using the same procedure outlined above. Using the two binary numbers X = 1010100 and Y = 1000011, we perform the subtraction X - Y and Y - X using 2's complemenfs:

                                X= 1010100

2' s complement of Y = +0111101

Topics You May Be Interested In
Fixed-point Representation Binary Adder
Arithmetic Addition Binary Adder-subtractor
Arithmetic Subtraction Binary Lncrementer
Other Decimal Codes Instruction Codes
Memory Transfer Instruction Cycle

                          Sum = 10010001

Discard end carry 27 = - 10000000

           Answer: X - Y = 0010001

                               y = 1000011

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Introduction To Decimal Representation Operation Code
Complements Indirect Address
Integer Representation Program Counter
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 2's complement of X = +0101 100

                          Sum = 1101111

There is no end carry

Answer is negative 0010001 = 2's complement of 1101111

Topics You May Be Interested In
Octal And Hexadecimal Number Conversion Other Binary Code
Alphanumeric Representation Binary Adder
Complements -2 Binary Lncrementer
Integer Representation Register-reference Instructions
Flow Control Sta: Store Ac & Bun: Branch Unconditionally

Frequently Asked Questions

Ans: The direct method of subtraction taught in elementary schools uses the borrow concept. In this method we borrow a 1 from a higher significant position when the minuend digit is smaller than the corresponding subtrahend digit. view more..
Ans: The r's complement of an n-digit number N in base r is defined as r' - N for N * D and D for N = D. Comparing with the (r - I)'s complement, we note that the r's complement is obtained by adding I to the (r - I)'s complement since r' - N = [(r' - I) - N] + I. view more..
Ans: Complements are used in digital computers for simplifying the subtraction operation and for logical manipulation. There are two types of complements for each base r system: the r's complement and the (r - l)'s complement. view more..
Ans: Since we are dealing with unsigned numbers, there is really no way to get an unsigned result for the second example. view more..
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Ans: Subtraction of two signed binary numbers when negative numbers are in 2' s complement form is very simple and can be stated as follows: Take the 2's complement of the subtrahend (including the sign bit) and add it to the minuend (including the sign bit). A carry out of the sign bit position is discarded. view more..
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Ans: Parity generator and checker networl<s are logic circuits constructed with exclusive-OR functions. This is because, as mentioned in Sec. 1·2, the exclusive-OR function of three or more varia.bles is by definition an odd function. An odd function is a logic function whose value is binary 1 if, and only if, an odd function number of variables are equal to 1. According to this definition, the P( even) is the exclusive-OR of x, y, and l because it is equal to 1 when either one or all three of the variables are equal to I (Table 3-7). The P(odd) function is the complement of the P(even) function. view more..

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