Microprocessor 8085 program to find 2's complement

In the third year of the B.Sc. Physics practical program under TANSCHE, it's crucial to grasp how microprocessors work. A significant part of this involves the Microprocessor 8085, which is a popular 8-bit processor. In this experiment, students get to practice basic arithmetic operations.

This blog post will highlight the experiment on finding the 2's complement of 8-bit/16-bit Numbers using the Microprocessor 8085. This hands-on activity helps students dive into the essential features of the 8085 microprocessor, including programming logic and memory functions. By completing this task, you'll develop a clear understanding of how the 8085 processes data and performs arithmetic operations, laying a strong groundwork in microprocessor systems.

Microprocessor 8085 program to find 2's complement

Aim:

Write an assembly language program to find 2’s complement numbers using microprocessor 8085.

Apparatus required:

Microprocessor 8085 kit, power supply etc

Program:

2’s complement of 8-bit

Memory address	Machine code	Mnemonics	Operands	Comments
8000	3A	LDA	8501H	Load the data in accumulator
8001	01
8002	85
8003	2F	CMA		Complement the accumulator
8004	3C	INR	A	2’s complement of the number
8005	32	STA	8502H	Store the result in the memory location 8502
8006	02
8007	85
8008	76	HLT		Stop the program

Example:

2’s complement of 8-bit number

First input location 8501H - 14H (In binary form 0001 0100) + 1

Result location 8502H - ECH (In binary form (1110 1100)

YouTube Demo:

2’s complement of 16-bit

Memory address	Machine code	Mnemonics	Operands	Comments
8000	21	LXI	H, 8501H	Address of the LSB of the number
8001	01
8002	85
8003	06	MVI	B, 00H	B register to store carry
8004	00
8005	7E	MOV	A, M	Move LSB from memory to accumulator
8006	2F	CMA		1’s complement of LSB
8007	C6	ADI	01	2’s complement of LSB
8008	01
8009	32	STA	8503H	Store the LSB to 8503H
800A	03
800B	85
800C	D2	JNC	8010H	Is No-carry? Go to 8010H
800D	10
800E	80
800F	04	INR	B	Increment B register by 1
8010	23	INX	H	MSB of the number
8011	7E	MOV	A, M	Move LSB from memory to accumulator
8012	2F	CMA		1’s complement of LSB
8013	80	ADD	B	Add this to register B
8014	32	STA	8504H	Store the MSB to 8504H
8015	04
8016	85
8017	76	HLT		Stop the program

Example:

2’s complement of 16-bit number

First input location 8501H - 14H (In binary form 0001 0100)

Second input location 8502H - 15H (In binary form 0001 0101)

Result location 8503H - EAH (In binary form (1110 1011)

Result location 8504H - ECH (In binary form (1110 1010)

YouTube Demo:

Procedure:

Result: 

The assembly programmes for microprocessor 8085 for finding the 2’s complement of 8-bit/16-bit numbers were written and executed using the microprocessor 8085 kit.

Click here for 1's complement
For further reading:
External site