8085 program to swap two 16-bit numbers using Direct addressing mode

In this program we will see how to swap two 16-bit numbers in direct addressing mode.

Problem Statement

Write 8085 Assembly language program to swap two 16-bit number stored at location 8000H – 8001H and 8002H – 8003H using direct addressing mode.

Discussion

Here we are swapping the values using XCHG instruction. This instruction swaps the contents of DE and HL pair contents. We are taking the first number into DE register pair, then the second number into HL pair, then by XCHG we are swapping them.

Input

Address	Data
. . .	. . .
8000	CD
8001	AB
8002	34
8003	12
. . .	. . .

Flow Diagram

Program

Address	HEX Codes	Mnemonics	Comments
F000	2A, 00, 80	LHLD 8000H	Load the first number into HL
F003	EB	XCHG	Exchange DE and HL
F004	2A, 02, 80	LHLD 8002H	Load the second number into DE
F007	22, 00, 80	SHLD 8000H	Store the second number at first position
F00A	EB	XCHG	Exchange the DE and HL
F00B	22, 02, 80	SHLD 8002H	Store the first number at second position
F00E	76	HLT	Terminate the program