8085 program to multiply two 8 bit numbers

Problem – Multiply two 8 bit numbers stored at address 2050 and 2051. Result is stored at address 3050 and 3051. Starting address of program is taken as 2000.

Example –

Algorithm –

1. We are taking adding the number 43 seven(7) times in this example.
2. As the multiplcation of two 8 bit numbers can be maximum of 16 bits so we need register pair to store the result.

Program –

Memory Address	Mnemonics	Comment
2000	LHLD 2050	H←2051, L←2050
2003	XCHG	H↔D, L↔E
2004	MOV C, D	C←D
2005	MVI D 00	D←00
2007	LXI H 0000	H←00, L←00
200A	DAD D	HL←HL+DE
200B	DCR C	C←C-1
200C	JNZ 200A	If Zero Flag=0, goto 200A
200F	SHLD 3050	H→3051, L→3050
2012	HLT

Explanation – Registers used: A, H, L, C, D, E

1. LHLD 2050 loads content of 2051 in H and content of 2050 in L
2. XCHG exchanges contents of H with D and contents of L with E
3. MOV C, D copies content of D in C
4. MVI D 00 assigns 00 to D
5. LXI H 0000 assigns 00 to H and 00 to L
6. DAD D adds HL and DE and assigns the result to HL
7. DCR C decreaments C by 1
8. JNZ 200A jumps program counter to 200A if zero flag = 0
9. SHLD stores value of H at memory location 3051 and L at 3050
10. HLT stops executing the program and halts any further execution

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