Computer’s Little Tales—1

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The computer instruction

The “computer instruction” is a sentence

(Like any sentence in our human languages)

But it is written in accurate 010101 code

With rigid discipline and mathematical accuracy

Using these instructions a human engineer speaks

To CPU which is the computer’s brain

The instruction is written in special technical code

Using English like “reserved words”

And also symbols like comma,full stop,

Brackets and quotation marks.

When a person is asked to do a work

We generally tell him somewhat like this

“First do this work….

“Then do that work

“Then go to that place…..

“Then meet that man….”

And so on and so forth

Similarly when solving an algebra problem

We write several steps in the working

The problem is solved step by step.

Same is the case with a “computer program”.

The “program” is nothing

But a set of rigid and serially numbered “instructions”

Sent by human engineer to the CPU

The CPU is not a living thing.

It has no thinking brain like humans.

It is only a slave of the human engineer

And fixed inside computer

To implement the person’s written instructions

Without the least little mistake

Its” thinking and actions”

Are only standard electric pulses

Corresponding to the “instructions”

Each instruction is implemented

Through several standard “microinstructions”

Prepared by the manufacturer of computer

And automatically preloaded

Into a specified section of the “main memory board”.

It is like a standardized “guide book”

Loaded on the main memory board.

This makes us feel as if CPU has a brain like humans.

It may first send hundreds of routine electric pulses

To different parts and gets only yes/no replies

If response is “yes” it switches one circuit .

If response is “no” it switches another circuit.

The so called intelligent work of CPU ,

It is all just a chain of switching.

Nothing magical in it.

It is all the intelligence of the man behind the machine.

Let us take example from real life,

To understand “micro instructions”.

You are sitting in a chair in your study.

You wish to take a book from the rack.

Your brain orders legs to make you stand

And alerts your eyes to closely coordinate.

Your legs start a small walk

And then stop at the rack.

The muscles of your hand are ordered to stretch

And the muscles in the fingers too

Then fingers grip the book

The book is securely held by the hand,

Then your legs walk back

And then your body comes to sitting posture

While your fingers grip the book

And place it in your lap to prepare you to study it.

All these are only a few of the micro operations.

There may be several dozens more.

The list of standard “micro instructions”

Are loaded by the “operating system”

The “operating system”, affectionately called OS

By all the folks using the computer,

Is only a part of the CPU .

The CPU issues endless sets of electric pulses

Which activate main memory, registers and the alu

This is the way the CPU commands other parts

It is really the chief switching engineer.


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