8085 program to find 1's and 2's complement of 16-bit number

In this program we will see how to find 1's complement and 2's complement of a 16-bit number.

Problem Statement

Write 8085 Assembly language program to find 1's complement and 2's complement of a16-bit number stored in 8000H and 8001H.

Discussion

8085 has an instruction CMA. This instruction complements the content of Accumulator. For 1's complement CMA instruction is sufficient, and for 2's complement we have to increase the number by 1 after complementing.

For 16-bit number, we are taking the number into HL pair, but for complementing we have to copy the numbers to Accumulator from H and L one by one. Then by INX instruction we will increase HL pair to get 2's complement

We are taking the number from 8000H and 8001H, and storing the 1's complement at location 8050H and 8051H, and 2's complement to 8052H and 8053H.

Input

Address	Data
. . .	. . .
8000	CD
8001	AB
. . .	. . .

Flow Diagram

Program

Address	HEX Codes	Mnemonics	Comments
F000	2A, 00, 80	LHLD 8000H	Load the number from memory to HL
F003	7C	MOV A, H	Load the H content to A
F004	2F	CMA	Complement the accumulator
F005	67	MOV H, A	Replace H with A
F006	7D	MOV A, L	Load the L content to A
F007	2F	CMA	Complement the accumulator
F008	6F	MOV L, A	Replace L with A
F009	22, 50, 80	SHLD 8050H	Store the 1's complemented result
F00C	23	INX H	Increase HL by 1
F00D	22, 52, 80	SHLD 8052H	Store the 2's complemented result
F010	76	HLT	Terminate the program