Non Restoring Division Algorithm in Computer Architecture

Non-Restoring Division Algorithm – The restoring method that we have discussed in this article, Restoring Division Algorithm, restores the partial remainder by adding the divisor to the negative difference. This method can be improved by avoiding the need for restoring after an unsuccessful subtraction. The new method is named the non-restoring division method.

Consider the sequence of operations that take place after the subtraction operation in the restoring division method. If A is positive, then perform shift left (A ← 2A) and subtract M (A ← A – M). It means the micro operation A ← 2A – M is performed. If A is negative, in the non-restoring method, leave it (A-M) as it is. The next time around the loop, the number is shifted left, and M is added to give
2A-M [2 (A-M)+M = 2A-2M+M = 2A-M], which is the same as before.

Non-Restoring Division Implementation

The hardware implementation of non-restoring division is similar to restoring division, and it is shown in the figure below.

Non-Restoring Division Algorithm

In the non-restoring method, the divisor (M) is not added to register A if the difference is negative, but instead, the negative difference is shifted left, and the divisor is added. The flow chart shown in the figures below gives the non-restoring division algorithm.

---

Q&A Section