AIM: Write a program to find 2‘s complement of an 8 bit number.

Objective:

• To understand the complement process
• To write algorithm for 1’s complement
• To develop the assembly language program to find 2’s complement
• To analyse the result and interpret errors if any

Requirement:

• Operating System- Windos, Linux
• 8085 simulator

Theory

2’s complement of a number is found in following ways:

• Do the 1’s complement of the given number
• Add ‘1’ to this 1’s complement

Example:

Find the 2’s complement of 59h

Number 59h                       =  01011001

1’s complement               = 10100110

Adding ‘1’ = 10100110 + 1 = 10100111

So, 2’s complement of 59h = A7h

Algorithm:

• Get a number in the accumulator
• Complement using CMA
• Add ‘1’ to this to get 2’s complement
• Save the result

Assembly language Program

 

Address	OP-CODE	Operands	Label	Mnemonic	Comments
4200	C3 05 042			JMP start
4203	F0		X:	db  0F0h
4204	00		Y:	Db 00h
4205	00		Start:	NOP
4206	21 03 042			LXI H, X
4209	11 04 042			LXI D, Y
420C	7E			MOV A,M
420D	2F			CMA
420E	C6 01			AdI 01
4210	12			STAX D
4211	76			HLT
Result