Instruction Format

Instruction Format :

what is instruction ?

ans:instruction is a command  to the microprocessor to perform a given task on a specified data.
Each  instruction has two parts:
(a)one is task to be performed,called the operation code..(op-code)
(b)the second is the data to be operated on ,called the operand.

THE  8085 ,instruction set is classified  into the following groups according to length..:

(1) 1-byte instructions:
A one byte instruction includes the op-code and operand in the same  byte.
example  :

MOV   B,  A


(2)2-byte instructions:
in a two byte instruction ,the first byte specifies the operation code and the second byte specifies the operand..

example:

MVI  A , 40H

(3)3-byte instructions:
in a three byte instruction ,the first byte specifies ,the op-code and the following two bytes specify the 16-bit address or 16bit-data.

example:

LXI H , 9000H