BASIC ELEMENT OF ASSEMBLY LANGUAGE

BASIC ELEMENTS OF ASSEMBLY LANGUAGE

a.       RESERVED WORDS

Reserved words are word that has special meaning in assembly language and can be used in their correct content. There are different types of reserved words:

i.                     Instructions mnemonics such as MOV, ADD and MUL.

ii.                   Register names.

iii.                  Directives, which tell assembler how to assemble programs.

iv.                 Attributes, which provide size and usage information for variables and operands e.g. byte and word.

v.                   Predefined symbols such as @data, which return constant integer values at assembly time.

b.      IDENTIFIERS

An identifier is a programmer chosen name. It might identify a variable, a constant, a procedure or a code label. Rules for creating identifiers are as follows:

i.                     They may contain between 1 and 247 characters.

ii.                   They are not case sensitive.

iii.                  The first character must be a letter (A-Z or a-z), underscore(_), ? or $. Subsequent characters may also be digits.

iv.                 An identifier cannot be the same as an assembler reserved word.

Examples of valid identifiers in assembly language are:Var1, Count, $first. _main, MAX, open_file, my File, xVal, _12345, etc.