Question

0-1 give the result as: (a)0 (b) 0 borrow 1. (c) 0 carry 1 (d) 1 and borrow 1
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Answer 1

Answer:

Explanation:

As their name implies, a Binary Subtractor is a decision making circuit that subtracts two binary numbers from each other, for example, X – Y to find the resulting difference between the two numbers.

Unlike the Binary Adder which produces a SUM and a CARRY bit when two binary numbers are added together, the binary subtractor produces a DIFFERENCE, D by using a BORROW bit, B from the previous column. Then obviously, the operation of subtraction is the opposite to that of addition.

We learnt from our maths lessons at school that the minus sign, “–” is used for a subtraction calculation, and when one number is subtracted from another, a borrow is required if the subtrahend is greater than the minuend. Consider the simple subtraction of the two denary (base 10) numbers below.

  123 X  (Minuend)

– 78 Y  (Subtrahend)

45 DIFFERENCE  

We can not directly subtract 8 from 3 in the first column as 8 is greater than 3, so we have to borrow a 10, the base number, from the next column and add it to the minuend to produce 13 minus 8. This “borrowed” 10 is then return back to the subtrahend of the next column once the difference is found. Simple school math’s, borrow a 10 if needed, find the difference and return the borrow.

The subtraction of one binary number from another is exactly the same idea as that for subtracting two decimal numbers but as the binary number system is a Base-2 numbering system which uses “0” and “1” as its two independent digits, large binary numbers which are to be subtracted from each other are therefore represented in terms of “0’s” and “1’s”.

Binary Subtraction