Question

Identify and correct a linear and a subroutine programming error in given fragments of program to find the factorial of a number

ORG 0000H
LJMP 8000H
ORG 8000H
MOV A, 04H;
MOV R0, @A;
LCALL 8000H;
LCALL 3000H ;

ORG 9000H ;
FACT: CJNE R0, #01H, NEXT ;
RET;
NEXT: DEC R0 ;
MOV B, R0 ;
MUL AB ;
MOV R5, A
LJMP 9000H ;
END ;

Answer 1

The correct program is:

Address	Label	Instruction	Comments
		ORG 0000H
0000H		LJMP 8000H	Long jump at location 8000H
		ORG 8000H
8000H		MOV A,#04H	MOV data 04H into A register
8002H		MOV R0,A	copy A into R0
8003H		LCALL 9000H	Long call at the location 9000H
8006H		SJMP 8006H	Short jump at 8006H location
		ORG 9000H
9000H	FACT:	CJNE R0, #01H, NEXT	compare R0 with 01H and jump at Next Label if R0 not equal to 01H
9003H		RET	Return to main prorram
9004H	NEXT:	DEC R0	Decrement R0 by 1
9005H		MOV B, R0	Copy R0 into B
9006H		MUL AB	Multiply A and B
9007H		MOV R5, A	Store data of A into the register R5
9008H		LJMP 9000H	Long jump into 9000H
900BH		END	End of program