8085 program to add 2-BCD numbers

In this program we will see how to add two 8-bit BCD numbers.

Problem Statement

Write 8085 Assembly language program to add two 8-bit BCD number stored in memory location 8000H – 8001H.

Discussion

This task is too simple. Here we are taking the numbers from memory and after adding we need to put DAA instruction to adjust the accumulator content to decimal form. The DAA will check the AC and CY flags to adjust a number to its decimal form.

Input

Address	Data
...	...
8000	99
8001	25
...	...

Flow Diagram

Program

Address	HEX Codes	Labels	Mnemonics	Comments
F000	21, 00, 80		LXI H,8000H	Point to first operand
F003	7E		MOV A, M	Load A with first operand
F004	23		INX H	Point to next operand
F005	86		ADD M	Add Acc and memory element
F006	27		DAA	Adjust decimal
F007	21, 50, 80		LXI H,8050H	Locate destination address
F00A	77		MOV M, A	Store the result into memory
F00B	D2, 12, F0		JNC DONE	If CY = 0, jump to Done
F00E	3E, 01		MVI A, 01H	Load 01H into Acc
F010	23		INX H	Point to next location
F011	77		MOV M,A	Store the carry
F012	76	DONE	HLT	Terminate the program