Computer's Little Tales—4

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THE VARIABLES IN ALZEBRA AND COMPUTER PROGRAM–B

Let us write a computer program

(Remember that a computer program

Simply speaking is a “set of orders “

Given by human engineer to the CPU

And written on the main memory board

After being translated into 010101 code )

Some English words called “reserved words” are also used

They are code names for some basic electric circuits.

Or for complicated mathematical circuits.

Some times even a comma,bracket,full stop etc

Can switch on or switch off a big circuit!

Remember that all instructions

Including such specially meaning punctuation marks

are translated Internally by special computer parts

into the 010101 code intelligible to the CPU.

There is also a very important fact.

From the moment we switched on the computer

The CPU starts sending hundreds or perhaps thousands

Of routine electric pulses to all parts

And only if “all is well” it sends

An “I am ready” message to the human engineer

(When only the MSDOS was in vogue

This “I am ready” message showed up

As the familiar “MSDOS prompt”)

The detailed internal processes

To make itself ready for use by the human engineer

Is called a “boot strap program”

And its meaning is obvious to all.

Then only we can start mathematical work

By typing code word “begin”

Or an equivalent word

(Similarly at the very end of program the word “end”

Or a similar word is to be typed.

It marks the extreme end of the program

And switching of all circuits by CPU).

Nowadays a magnetic copy

Of the entire program from “begin” to “end”

Done by you is invariably kept stored

Or “saved” permanently in magnetic discs

Fixed inside computer itself.

It is in no way connected to main memory

But when required copy of it can be taken

Onto the main memory in a moment’s time!

Outside copies are also taken

And sent by business men to their central office

Otherwise the big banks and business offices

And big government departments

Can not keep watch on their daily work

But in the ancient days of 1940s

No such arrangements were available

Perhaps magnetic tapes could record

Some data under supervision of expert engineers.

Now let us study a simple computer program.

“1).begin program”

“2). Name four selected memory houses as X, Y, Z, K”

“3).formula is K=X-2Y+5Z”

“4). Give values x=30, y= 20, z=60”

“5).calculate K using above formula”

“6).Print value of k “

“7).end program”

Using this program you can get answer

Even for very big values of X,Y and Z

As easily as for small values.

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