8085 program to add three 16 bit numbers stored in registers

In this program we will see how to add three 16-bit numbers stored in register pairs.

Problem Statement

Write 8085 Assembly language program to add three 16-bit numbers stored in register pair BC, DE and HL. Store the result at DE register pair.

Discussion

In this program we are storing the 16-bit numbers into BC, DE and HL pair. We have DAD D instruction which helps to add HL and DE register pair, and store the result into HL pair. After that copy BC to DE, then again perform DAD D to add them. Finally using XCHG we are storing them into DE register pair.

Here we are adding 0502H + 1211H + 2133H = 3846H

Input

Register	Data
BC	0502
DE	1211
HL	2133

Flow Diagram

Program

Address	HEX Codes	Mnemonics	Comments
F000	01, 02, 05	LXI B,0502H
F003	11, 11, 12	LXI D,1211H
F006	21, 33, 21	LXI H,2133H
F009	19	DAD D	Add DE and HL, and Store into HL
F00A	50	MOV D,B	Copy B to D
F00B	59	MOV E,C	Copy C to E
F00C	19	DAD D	Add DE and HL (Actually BC), store into HL
F00D	EB	XCHG	Swap DE and HL
F00E	76	HLT	terminate the program