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.
THE “MAIN MEMORY” IS A BLACK BOARD
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.