Intoduction :- Elements of Assembly Language
Elements of Assembly Language – Assembly language is basically like any other language, which means that it has its words, rules and syntax. An assembly language is a machine dependent language, low level programming language which is specific computers.
Each statement is assembly language is corresponds to an instruction or declaration statement or directive to assembler. Compared to machine language, Assembly language basic facilities.
Mnemonic operation code :-
Also called as Mnemonic opcode. These are easier to remember and to use than numeric opcodes. They also enable Assemble to provide helpful dignosis. Fig. induction of misspelt operation code.
Symbolic code :-
Thus operands can be associat with data or instructions. This symbolic names can be use as operands. Assembler performs memory blinding to these names, programmer need not to know any details about memory blinding performed by assembler.
Data Declaration :-
Data can be declare in variety of notation, including decimal notation. This avoids manual conversion of constants into internal machine instructions. e.g conversion of – 5 into (11 111 010)
Elements of Assembly Language – Advance assembler directive
Syntax for origin is,
ORIGIN <address spec>
<address spec> is an <operand spec> or <constant>
This directive indicates that, IC should be set to address given by <address spec>.The origin statement is useful only when target program does not consists of consecutive memory words. The ability to use an <operand spec> in the origin statement is to perform L.C processing in the relative rather than absolute manner.
Syntax of EQU is,
<symbol> EQU <address spec>
The EQU statement defines the symbol to represent <address spec>. This differ from the DC/DS statement as no LC processing has implied. The EQU simply associate the name <symbol> with <address spec>.
It permits programmer to specify where literals should be placed by default assembler places the literals after END statement. At every LTORG and END statement, assembler aloocates memory to literals as literal pool.
This pool consists, all the literals used in a program since the start of program or since last LTORG statement.