8085 Multiplication Program Logic

The objective is to multiply the contents of register $B$ by the content of register $C$ and store the result in the accumulator $A$. This is achieved using repeated addition within a loop.

Initial values: Register $B$ = $0AH$, Register $C$ = $0BH$.

The program starts with initializing the accumulator $A$ to $00H$.

$MVI A, 00H$

Multiplication via Repeated Addition

Multiplication can be performed by repeatedly adding the multiplicand (content of $B$) to the accumulator $A$, for a number of times specified by the multiplier (content of $C$). Register $C$ serves as the loop counter.

Step-by-Step Program Execution

The loop needs to perform the following actions in each iteration:

1. Add the value of register $B$ to the accumulator $A$.
2. Decrement the loop counter in register $C$.
3. Check if the counter ($C$) has reached zero. If not, repeat the loop.

Considering the available options, the sequence that correctly implements these steps is:

1. $ADD B$: Adds the content of register $B$ to the accumulator $A$.
2. $DCR C$: Decrements the content of register $C$ by 1.
3. $JNZ LOOP$: Jumps to the label $LOOP$ if the result of the last $DCR C$ operation is not zero.

This sequence ensures that the addition happens, followed by the decrementing of the counter, and then the jump condition is checked. This correctly executes the addition $0BH$ times.

Therefore, the complete sequence to fill the gap is $ADD B, DCR C, JNZ LOOP$.

Program Structure:

$MVI A, 00H$

$LOOP: ADD B$

$ DCR C$

$ JNZ LOOP$

$HLT$

$END$