ASSEMBLY PROGRAMMING

ASSEMBLY PROGRAMMING

An assembly language, mostly abbreviated (ASM): this is a low level programmable device, in which there is a very strong (generally one-to-one) correspondence between the language and the architecture’s machine code instructions.

Advantages of assembly programming

• It requires less memory and execution time
•  It allows hardware – specific complex jobs in an easier way
• It is suitable for time-critical jobs.

Tools for Assembly Programming

• Assembler: – This is the most important tool for assembly language programming, it is a software that converts assembly language code into machine language.
• The Linker: – This is the output of the assembler, like that of any compiler, needs to be linked to form an executable file.

Note: Assembly language programs consist of three types of statement

• Executable instruction or instructions: These are statement of commands that tells the processor what to do.
• Assembler directives or pseudo-ops: This tells the assembler about the various aspects of the assembly process.
• Macros: Macro are basically a text substitution mechanism.
• Memory segments – A segmented memory model divides the system memory into groups of independent segments referenced by pointers located in the segment registers. Each segment is used to contain a specific type of data. One segment is used to contain instruction codes (code segment) another segment stores the data elements (Data segment) and a third segment keeps the programme flags and some other conditional instructions that test the value of these status flags to take the control flow to other location.
• Segment Register: Segments are specific areas defined in a program for containing data, code and stack. The segment registers stores the starting addresses of a segment. To get the exact location of data or instruction within a segment, an offset value (or displacement) is required.