This preview shows page 1. Sign up to view the full content.
Unformatted text preview: y
detect and indicate errors for use of an invalid mnemonic op-code or a name that
has never been defined. For example, suppose an assembly language program
instruction reads ADD AREA, and we forget to define AREA in the program, the
assembler will look through its table to find AREA and not finding it will indicate
the error. 3. Easier to modify. Because they are easier to understand, it is easier to locate,
correct, and modify instructions of an assembly language program than a machine
language program. Moreover, insertion or removal of certain instructions from the
program does not require change in the address part of the instructions following
that part of the program. This is required in case of machine language.
4. No worry about addresses. One of the greatest advantage of assembly language
is that programmers need not keep track of the storage locations of the data and
instructions while writing an assembly language program.
The importance of
this advantage can be best illustrated with an example. Suppose we have written a
long machine language program involving many instructions and several
references to itself within the program, such as looping, branching, and so on. At
the very end we may suddenly discover that we have left out an instruction in the
middle. If we insert that instruction, we will have to go through the entire program
to check and modify (if necessary) all references to other instructions. This is
certainly a tedious job. But if we write the same program in assembly language,
we merely add the extra instruction, and the assembler will take care of
automatically modifying the references suitably.
5. Easily relocatable. The availability of pseudo-instructions for instructing the
system how we want the program to be assembled inside the computer's memory
makes assembly language programs easily relocatable because their location can
be easily changed merely by suitably changing the pseudo-instructions. This is
not easily possible with machine language programming. This feature can be best
illustrated with the help of an example. Suppose that an assemb...
View Full Document
This document was uploaded on 04/07/2014.
- Spring '14