INSTRUCTION

 INSTRUCTION

                     An instruction is the most basic operation that a computer carries out. The parser and compiler break down a program written in a high level language such as Java into machine instructions, i.e., operations that can be understood by the system.

   

For example, consider the following Java code:

a = a + 10;this code tells the computer to increment the value of a by 10.But the computer has no means of carrying out this operation directly.

So, the parser and compiler reduce this command to a series of step by step instructions as follows: R1 = R2; R3 = 10; R4 = R2 + R3; R1 = R4;

 Here, the value of a is initially stored in the register R2.Registers are the basic memory cells that the CPU deals with directly. They physically contain numeric values, which can be manipulated as above.