Chapter 4, Problem 38E

Explanation of Solution

Arithmetic example:

Example using two registers:

The addition of two numbers is an arithmetic example of this. The RTN for MARIE code for addition of two numbers using two registers is as follows:

$\begin{array}{l}\text{Load A:MAR}\leftarrow \text{A}\\ \text{ MBR}\leftarrow \text{M[MAR]}\\ \text{ AC}\leftarrow \text{MBR}\\ \text{Add B: MAR }\leftarrow \text{B}\\ \text{ MBR}\leftarrow \text{M[MAR]}\\ \text{ AC}\leftarrow \text{AC+MBR}\end{array}$

Here, the address and buffer registers carry the operations sequentially.  So, the every operations takes “x” amount of time.

Hence the total time taken for the RTN is “6x” where “x” specifies the amount of time