<< Chapter < Page Chapter >> Page >
This module will provide a brief introduction into Assembly Language.

Assembly language

Assembly language , commonly referred to as assembly, is a more human readable form of machine language. Every computer architecture uses its own assembly language. So processors using an architecture based on the x86, PowerPC, or TI DSP will each use their own language. Machine language is the pattern of bits encoding a processor's operations. Assembly will replace those raw bits with a more readable symbols call mnemonics .

For example, the following code is a single operation in machine language. 0001110010000110 For practical reasons, a programmer would rather use the equivalent assembly representation for the previous operation. ADD R6,R2,R6 ; Add $R2 to $R6 This is a typical line of assembly. The op code ADD instructs the processor to add the operands R2 and R6 , which are the contents of register R2 to register R6, and store the results in register R6. The " ; " indicates that everything after that point is a comment, and is not used by the system.

Assembly has a one-to-one mapping to machine language. Therefore, each line of assembly corresponds to an operation that can be completed by the processor. This is not the case with high-level languages. The assembler is responsible for the translation from assembly to machine language. The reverse operation is completed by the dissasembler .

Assembly instructions are very simple, unlike high-level languages. Often they only accomplish a single operation. Functions that are more complex must be built up out of smaller ones.

The following are common types of instructions:

  • Moves:
    • Set a register to a fixed constant value
    • Move data from a memory location to a register (a load) or move data from a register to a memory location (a store). All data must be fetched from memory before a computation may be performed. Similarly, results must be stored in memory after results have been calculated.
    • Read and write data from hardware devices and peripherals
  • Computation:
    • Add, subtract, multiply, or divide. Typically, the values of two registers are used as parameters and results are placed in a register
    • Perform bitwise operations, taking the conjunction/disjunction (and/or) of corresponding bits in a pair of registers, or the negation (not) of each bit in a register
    • Compare two values in registers (>,<,>=, or<=)
  • Control Flow:
    • Jump to another location in the program and execute instructions there
    • Jump (branch) to another location if a certain condition holds
    • Jump to another location, but save the location of the next instruction as a point to return to (a call)

Advantages of assembly

The greatest advantage of assembly programming is raw speed. A diligent programmer should be able to optimize a piece of code to the minimum number of operations required. Less waste will be produced by extraneous instructions. However, in most cases, it takes an in-depth knowledge of the processor's instruction set in order to produce better code than the compiler writer does. Compilers are written in order to optimized your code as much as possible, and in general, it is hard to write more efficient code than it.

Low-level programming is simply easier to do with assembly. Some system-dependent tasks performed by operating systems simply cannot be expressed in high-level languages. Assembly is often used in writing device drivers , the low level code that is responsible for the interaction between the operating system and the hardware.

Processors in the embedded space, such as TI's MSP430 , have the potential for the greatest gain in using assembly. These systems have very limited computational resources and assembly allows the maximum functionality from these processors. However, as technology is advancing, even the lowest power microcontroller is able to become more powerful for the same low cost.

Questions & Answers

where we get a research paper on Nano chemistry....?
Maira Reply
what are the products of Nano chemistry?
Maira Reply
There are lots of products of nano chemistry... Like nano coatings.....carbon fiber.. And lots of others..
Even nanotechnology is pretty much all about chemistry... Its the chemistry on quantum or atomic level
no nanotechnology is also a part of physics and maths it requires angle formulas and some pressure regarding concepts
Preparation and Applications of Nanomaterial for Drug Delivery
Hafiz Reply
Application of nanotechnology in medicine
what is variations in raman spectra for nanomaterials
Jyoti Reply
I only see partial conversation and what's the question here!
Crow Reply
what about nanotechnology for water purification
RAW Reply
please someone correct me if I'm wrong but I think one can use nanoparticles, specially silver nanoparticles for water treatment.
yes that's correct
I think
Nasa has use it in the 60's, copper as water purification in the moon travel.
nanocopper obvius
what is the stm
Brian Reply
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
How we are making nano material?
what is a peer
What is meant by 'nano scale'?
What is STMs full form?
scanning tunneling microscope
how nano science is used for hydrophobicity
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
what is differents between GO and RGO?
what is simplest way to understand the applications of nano robots used to detect the cancer affected cell of human body.? How this robot is carried to required site of body cell.? what will be the carrier material and how can be detected that correct delivery of drug is done Rafiq
analytical skills graphene is prepared to kill any type viruses .
Any one who tell me about Preparation and application of Nanomaterial for drug Delivery
what is Nano technology ?
Bob Reply
write examples of Nano molecule?
The nanotechnology is as new science, to scale nanometric
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
what school?
biomolecules are e building blocks of every organics and inorganic materials.
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
Privacy Information Security Software Version 1.1a
Berger describes sociologists as concerned with
Mueller Reply
what is hormones?
Got questions? Join the online conversation and get instant answers!
Jobilize.com Reply

Get the best Algebra and trigonometry course in your pocket!

Source:  OpenStax, Microcontroller and embedded systems laboratory. OpenStax CNX. Feb 11, 2006 Download for free at http://cnx.org/content/col10215/1.29
Google Play and the Google Play logo are trademarks of Google Inc.

Notification Switch

Would you like to follow the 'Microcontroller and embedded systems laboratory' conversation and receive update notifications?