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Re: [OCLUG-Tech] What does a computer do?

Hi Scy;

I appreciate the time and thought that you put into your reply.  While
admit that I am still trying to think things through, your comments
bring a couple of ideas to mind.

On Sun, 2006-23-04 at 11:56 -0400, sberaud wrote:
> You have been both overly specific and overly general in the same 
> paragraph ;)
> 

Yes, I somewhat agree, particularly when compared to definitions that I
have read elsewhere.  The reason I am trying to compose my own, geared
to my own use, and the use of any interested people trying to understand
computing at a deeper level than just applications, is to create an
understandable framework that can be used as an outline.  The definition
was not meant to be a philosophical discourse or a technical
introduction.  It was meant to be something useful -- and accurate. 


> I (simplistically) think of it this why.
> 
> Its is nothing more that a giant sophisticated calculator, that does 
> nothing but add and subtract ones and zeros.
> 
> It can answer such questions as: "yes or no", "0 or 1", "off or on".
> 
> You can look at a bit of information as being in one of two states, on 
> or off. By using a series of bits we can confer larger amounts of 
> information across a system bus (lanes in a highway), from data storage 
> devices such as memory, optical or magnetic media. We group bits in to 
> packages called "words" or bytes, but they are arbitrary. A computer 
> calculates values based on logic that is programmed via a set of 
> instructions based on the events we define, and interpreted by a set of 
> hard wired "logic" (yes or no) paths within the cpu.

For example, your paragraph above, only gives me the opportunity of
writing one small paragraph or section in response to the question "How
does a computer work?" or "What does a computer do?".  Further, it would
probably of secondary interest or only passing interest to someone
exploring their computer -- important as understanding the binary system
and Boolean logic is.

Because of your and other peoples comments I have changed the paragraphs
somewhat.

"A digital computer is an appliance that takes in information meaningful
to humans; converts it into electrical data; stores it; may or may not
transform the data; and presents it as information to humans.

I used the term 'digital computer ' to avoid dealing with too
generalized concepts such as an abacus, a von Neuman machine or a
Turning machine.  If necessary they can be explained later.

I used the term 'appliance ' to interject some ordinariness and
acceptability into the concept of computing and to emphasis that it is
an ordinary machine like any other household machine that is powered by
wall socket electricity. 

I used the terms 'information meaningful to humans ' to avoid things
like information theory and to set up a distinction between the stuff we
do, think, and use every day outside of the computer and the binary data
that exists inside the machine that almost always has no relevance to a
computer user.  'meaningful' implies (I think) something apparent to
human senses, such as sounds, colours, text, numbers etc. 

"converts it into electrical data" leads into a discussion of I/O and
I/O peripherals, equipment and problems.  As well, the phrase has a
non-threatening appeal.  The concept of appliances converting
electricity into something useful (e.g. stoves converting electricity
into heat, light bulbs converting electricity into light or vacuum
cleaners converting electricity into suction) is an acceptably ordinary
concept.

"stores it" is probably the most important concept to users.  Once some
information is put there; it stays there; available for future use.

"may or may not transform the data" to most people, this is what a
computer does.  It is why it is useful and prepares readers to accept
long explanations of what kind of transformations can be made and how
they can be useful. 

And, "presents it as information to humans" is the guarantee that my
saved, transformed stuff gets back to me. I should have written it as
'meaningful information ' perhaps but the repetition of meaningful
sounds redundant.

> I think the lego examples posted were designed to clarify the difference 
> between the principals of computing, (which is what you are trying to 
> understand it seems) vs the "mechanism" of computing, which is what you 
> were describing with the change in voltages (which is the physical 
> process of a semi-conductors and solid state electronics) which 
> represent the values of 1, 0; on, of; yes, no. You could just as easily 
> have logic devices based on water taps or rubber bands. The machine is 
> secondary to the principal.

The Lego examples *are* impressive and I do intend to use them in my
explanations of Boolean logic and gates.  I wish I had found them
earlier.  Thanks Mike.  However, I do feel that I have touched on the
type and form of electronic data sufficiently to lead into a fuller
discussion later without being too specific now.

The second paragraph expands on the first, defining 'data' and
'transform':

"Electrical data consists of a set, or continuous stream, of lower or
higher voltage pulses or bits. Data is stored, moved or transformed 
by transistors switching electrical data from one circuit to another.  
The possible transformations are: changing a higher voltage bit to 
a lower voltage and vice versa; arithmetic addition of two sets of 
data bits; and, moving data from one useful location to another useful 
location within the computer." 

Having brought 'electrical data ' into the definition I felt a short,
clear and succinct explanation was necessary.  I may be wrong but the
idea of a 'set' both in the mathematical sense and in the ordinary sense
of a bunch or group or collection can be absorbed by any reader without
extra deciphering of meaning, as can a 'continuous stream '.  

Most people understand what voltage is; at least, that it is somehow
involved with the electricity coming out of their wall.  'voltage pulses
or bits ' introduces the concept of for the first time of bits and
bytes.  A concept, which most people have heard of, but many don't know
what they are.  I believe it clearly establishes the binary nature of
electronic data without scaring people with a long dissertation on base
2 math systems.

"stored, moved or transformed by transistors" gets the magic word
'transistors' into the definition without intimidating.  Further,
'transistors' is tied to the simple idea of switches, which everyone
understands.

The last sentence gives me the most difficulty.  From everything I've
studied, at the most basic level, a computer only does those 3 simple
things.  If I have missed something, let me know.  As long as I am
accurate, I am trying to say that even when computers are at their most
complicated they are still only simple machines.

This response is long winded I know.  But, it did give me a chance to
more clearly think through what I had written and make minor
corrections.

Regards Bill