How The First Cpu Was Organised —1

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The times when there was no CPU at all

The first electronic calculator

Of the times before Dr.von Neumann

(That is before the nineteen forties)

Was at best only a complicated array

Of “intelligent” mathematical circuits.

The circuits worked wonders no doubt

They could do the add/subtract

And the multiply /divide operations with ease.

But they were just a jumble of wires,

Blinking bulbs and magnetic tapes,

And a few thousand diodes and triodes.

There was no internal central command

There was no central circuit

To manage all internal procedures.


The work of bringing in data

To mathematics-doing logic circuits

And switching thecircuits in the required order

Was entirely done by the outside human engineer

The engineer would spend hours and hours

Sitting before the machine and often felt confused

Watching the rows of blinking bulbs

And working out the reply code of zeroes and ones

Contained in the rows of blinking bulbs.

In the first experimental machines

The engineer perhaps had to operate

A hundred switches in a minute

For inputting data for a mathematical problem

Or struggle to decode the outputted answer data

Indicated by the rows of blinking bulbs.


Dr von Neumann laid out a detailed plan.

In those distant “ancient times” in the 1940s.

He wanted to make computing automatic

With most minimum human interference.

To achieve this aim he put

Inside the giant size calculator designed by him

(Which had thousands of the diodes and triodes)

Many important specialist parts

Called the CPU, the ALU and “the Memory”

But the “Memory” or more correctly

“The Programmable Main Memory”

Was the critical and most important part.

Remember here that the word “memory”

In computer world is equivalent to the “black board”

Which we see in a class room.

Or it is like the diary book which we use

To wrote down friends’ addresses, phone numbers etc,

All of which we can not remember.

The CPU was planned to be the commander- in- chief.

It enforced all the orders given by human engineer.

Let us also ask ourselves a question,

Where does the human engineer propose to record

The set of his instructions to the CPU?

The “main memory” board is the specific part

Created for writing his “instructions”

To the CPU in 010101 code.

The set of accurately coded “instructions”

Recorded by the human engineer

On the “main memory board”

Is called a “computer program”

The procedures Dr von Neumann devised

To write the “computer program”

Closely resembled the working steps

Written for solving an algebraic problem.

Each program consisted of about a dozen “instructions”

The “instructions” were serially numbered

Each was a string offortyzeroes and ones

In the first programs of the first calculators.

The “main memory board” is made of

Thousands of microscopic memory houses

Arranged on perpendicularly laid tiny “streets”.

Each memory house has eight or sixteen chambers

In a row like rooms of a soldier’s barrack

Each “memory house” is made of

Eight or sixteen of these tiny magnetic cores in a row.

The cores are tiny rings through which

Two thin perpendicular wires are passed.

The two wires are part of a wider mesh

(Of mutually perpendicular wires)

Passing through all the little iron cores.

It is indeed quite a technical feat

To construct such a huge number of cores

On a small plastic board and arrange them

Like a colony of houses in a mega city .

The city has such perfectly parallel

And perpendicular roads.


The set of mutually perpendicular wires

Bring in or take out current

And in the process keep each ring

Magnetized or demagnetized.

In the 010101 language every number

Or letter of alphabet or even a symbol like comma

Question mark or quotation mark

Is made of a set of eight or sixteen zeroes and ones

So a combination of eighteen or sixteen rings

(Some magnetized and some not magnetized )

Can represent a number or letter or symbol.

(In modern computers the “main memory” is made from

Millions of submicroscopic transistors

Etched on little silicon chips

Which are of the size of shirt buttons!

We have described these tiny transistors

In detail a little later on.



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