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Sequential memory or combination random/sequential memory isn't very useful for most computer programs at the inner working level because access to eachparticular piece of data is slow. As a result, most modern computers have random access memory that is used for storage and retrieval of data by programs whilethey are running and disks that are used for long-term storage and retrieval of data that needs to be saved over longer periods of time.

Variables

As the computer program performs its operations in the prescribed order, it is often necessary for it to store intermediate results somewhere in itsmemory and to retrieve those results later for use in subsequent operations. The intermediate results are often stored in little chunks of memory that werefer to as variables .

Brief definition of a variable

The following definition is paraphrased from Wikipedia .

In computer programming, a variable is a storage location and an associated symbolic name (an identifier) that contains some known or unknown quantity or information -- a value.
The variable name is the usual way to reference the stored value; this separation of name and content allows the name to be used independently of the exact information it represents.
The value stored in the variable may change during program execution.

A physical analogy

We can think of random access memory as being analogous to a metal rack containing a large number of compartments. The compartments are all the samesize and are arranged in a regular grid of rows and columns.

Each compartment has a numeric address printed above it. No two compartments have the same numeric address. Each compartment also has a little slot intowhich you can insert a name or a label for the compartment. No two compartments can have the same name.

Although the analogy is not perfect, we can think of one of those compartments as being analogous to a variable.

Pretend that you are a computer program

Think of yourself as a computer program. You have the ability to create labels for each compartment (variable) . You have the ability to write values on little slips of paper and to put them into the compartments. You also have the abilityto read the values written on the little slips of paper and to use those values for some purpose. However, there are four rules that you must observe:

  • You may not remove a slip of paper from a compartment without replacing it by another slip of paper on which you have written a value.
  • You may not put a slip of paper in a compartment without removing the one already there.
  • You may not give the same label or name to two or more compartments.
  • You may not change a label once you have assigned it to a compartment.

Names versus addresses

Although each compartment in the physical memory in the computer has a numeric address, as a programmer using a high-level programming language such as Scratch, you usually don't need to be concerned about the numeric addresses of the compartments. (The compartments are often referred to as locations in memory.)

Questions & Answers

where we get a research paper on Nano chemistry....?
Maira Reply
nanopartical of organic/inorganic / physical chemistry , pdf / thesis / review
Ali
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..
learn
Even nanotechnology is pretty much all about chemistry... Its the chemistry on quantum or atomic level
learn
Google
da
no nanotechnology is also a part of physics and maths it requires angle formulas and some pressure regarding concepts
Bhagvanji
hey
Giriraj
Preparation and Applications of Nanomaterial for Drug Delivery
Hafiz Reply
revolt
da
Application of nanotechnology in medicine
what is variations in raman spectra for nanomaterials
Jyoti Reply
ya I also want to know the raman spectra
Bhagvanji
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.
Damian
yes that's correct
Professor
I think
Professor
Nasa has use it in the 60's, copper as water purification in the moon travel.
Alexandre
nanocopper obvius
Alexandre
what is the stm
Brian Reply
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
Rafiq
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
Damian
How we are making nano material?
LITNING Reply
what is a peer
LITNING Reply
What is meant by 'nano scale'?
LITNING Reply
What is STMs full form?
LITNING
scanning tunneling microscope
Sahil
how nano science is used for hydrophobicity
Santosh
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
Rafiq
what is differents between GO and RGO?
Mahi
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
Rafiq
if virus is killing to make ARTIFICIAL DNA OF GRAPHENE FOR KILLED THE VIRUS .THIS IS OUR ASSUMPTION
Anam
analytical skills graphene is prepared to kill any type viruses .
Anam
Any one who tell me about Preparation and application of Nanomaterial for drug Delivery
Hafiz
what is Nano technology ?
Bob Reply
write examples of Nano molecule?
Bob
The nanotechnology is as new science, to scale nanometric
brayan
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Damian
Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
Renato
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
?
Kyle
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
Adin
why?
Adin
what school?
Kyle
biomolecules are e building blocks of every organics and inorganic materials.
Joe
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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Source:  OpenStax, Teaching beginners to code. OpenStax CNX. May 27, 2013 Download for free at http://cnx.org/content/col11498/1.20
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