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 |
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