Chapter 4, Problem 36E

Explanation of Solution

Subroutine to subtract two numbers:

The following code is to subtract two numbers with formal parameters “X” and “Y”. The input of the program is declared with actual parameter “A” and “B”. The program tests the subroutine “Subr” with two values.

The hexadecimal address starts with “100” in instruction.

100 Load A/Load the first value

101 Store X/Pass the first parameter “x”

102 Load B/Load the second value

103 Store Y/Pass the second parameter “y”

104 Jns Subr/Jump to “Subr” label with return

/address

105 Load X/Load the result

106 Output/Print the first difference

107 Load C/Load the first value

108 Store X/Pass the first parameter “x”

109 Load D/Load the second value

10A Store Y/Pass the second parameter “y”

10B Jns Subr/Jump to “Subr” label with return address

10C Load X/Load the result

10D Output/Print the second difference

10E Halt/Terminate the program

10F X, Dec 0/Input value of parameter “x”

110 Y, Dec 0/Input value of parameter “y”

111 A, Dec 10/Decla...