Basic Arithmetic Operation

Explanation

Here is the explanation of the assembly program:

1. Purpose

This program subtracts the value in Register B from the value in Register A (Accumulator). Since both registers hold the same value (25h), it demonstrates basic subtraction resulting in zero.

2. Key Concepts

• Immediate Data Transfer (MVI): Loading a specific value directly into a register.
• Accumulator Operations: Arithmetic operations in 8085 always modify the Accumulator (A).
• Flags: Operations like SUB update status flags (specifically setting the Zero Flag when the result is 0).

3. Code Walkthrough

• MVI A, 25h: Moves the immediate hexadecimal value 25h into Register A (Accumulator).
• MVI B, 25h: Moves the immediate hexadecimal value 25h into Register B.
• SUB B: Subtracts the content of Register B from Register A (A = A - B) and stores the result in Register A.
• HLT: Halts (stops) the execution of the processor.

4. Output

• Register A (Accumulator): 00h
• Zero Flag (ZF): 1 (Set to High, indicating the arithmetic result is zero)