Question

Write a program in which the number 5H is added 20 times and the result is finally stored in R0.

Answer 1

Solving the above problem in Assembly language for Micro controller 8051:

MOV R0, #05H; // Loading Register R0 with value 5H

MOV R1, #20H; // Using R1 as counter. Moving 20H to Register R1

MOV A, #00H; // Initialising Accumulator value with 00H

UP: ADD A, R0; // Adding 5H to Acc. value by creating a loop with lable UP

DJNZ R1, UP // Loop continues untill R1 counter value becomes 0. DJNZ will decrement R1 value by 1 and // jumps to label UP untill R1 becomes 0. Thus repetitive addition of 5H in Accumulator 20 times

MOV R0, A // Finally move the Accumulator result in Registor R0