# Multiply Two 16-bit Numbers in 8085 Microprocessor

In this tutorial, we will learn how to find the multiplication of two 16-bit numbers in 8085 Microprocessor? By Ayush Sharma Last updated : May 13, 2023

## 8085 Program to Multiply Two 16-bit Numbers

Given two 16-bit numbers, we have to find their multiplication in 8085 Microprocessor.

### Assumption

1. Starting address of program: 2000
2. Input memory location: 2050, 2051, 2052, 2053
3. Output memory location: 2054, 2055, 2056, 2057

### Algorithm

1. Load the first data in HL pair.
2. Move content of HL pair to stack pointer.
3. Load the second data in HL pair and move it to DE.
4. Make H register as 00H and L register as 00H.
5. ADD HL pair and stack pointer.
6. Check for carry if carry increment it by 1 else move to next step.
7. Then move E to A and perform OR operation with accumulator and register D.
8. The value of operation is zero, then store the value else goto step 3.

### Program

2003SPHLSAVE IT IN STACK POINTER
2007XCHGEXCHANGE HL AND DE PAIR CONTENT
2008LXI H,0000HH<-00H,L<-00H
200BLXI B,0000HB<-00H,C<-00H
200FJNC 2013JUMP NOT CARRY
2012INX BINCREMENT BC BY 1
2013DCX DDECREMENT DE BY 1
2014MOV A,EA<-E
2015ORA DOR THE CONTENT OF ACCUMULATOR AND D REGISTER
2016JNZ 200EJUMP NOT ZERO
2019SHLD 2054L<-2053,H<-2054
201CMOV L,CL<-C
201DMOV H,BB<H
201ESHLD 2056L<-2055,H<-2056
2021HLTENDS THE PROGRAM

### Explanation

Registers B, C, D, E, H, L and accumulator are used for general purpose.

2. SPHL: save the content of HL in stack pointer.
4. XCHG: exchange the content of HL pair with DE.
5. LXI H, 0000H: make H as 00H and L as 00H.
6. LXI B, 0000H: make B as 00h and C as 00H.
9. INX B: increments BC register with 1.
10. DCX D: decrements DE register pair by 1.
11. MOV A, E: move the content of register E to accumulator.
12. ORA D: or the content of accumulator and D register.
14. SHLD 2054: store the result to memory address 2054 and 2055 from HL pair register.
15. MOV L, C: move the content of register C to L.
16. MOV H, B: move the content of register B to H.
17. SHLD 2056: store the result to memory address 2056 and 2057 from HL pair register.
18. HLT: terminates the program.