How The First Cpu Was Organized-(4)

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The power of the “von Neumann machine”

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As long as a person is alive the vital functions like

Heart beat, blood flow, digestion andbreathing

Go on without his special attention.

Similarly as long as the computer is on

The CPU checks every second

All the electric connections inside

Though we who sit before computer

We are not aware of these vital activities of CPU.

When any person even casually

Presses a key on the key board,

The incoming 010101 code becomes for the CPU

An incoming “priority telephone call”

. It suspends all internal work

And shifts the data relating to its present wok

To a separate “memory board”

And takes required necessary action.

Only after fully checking such “interrupts”

It goes back to its previous internal work.

There is another very interesting basic fact

All the thousands of the tiny logic circuits,

Mathematical circuits and electric circuits

Work like a huge army stepping in unison

They are all controlled by a single time signal

The time pulse is generated by a special input

Given to all the “flip flop” chambers

By sending a third zero or one

At the back wall of every logic gate.

In normal way only two bits (zeros or ones)

Are sent at the “back wall” of a logic gate.

The extra “zero” or “one” generated thus

Creates a most perfect time signal

For all the internal parts.

miniaturisation

A word on the miniaturization of computer parts.

After use of transistor circuits

Which grew smaller year by year,

The computer’s CPU,ALU and the Main memory

Have all become tinier than shirt buttons !

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At the beginning of twentieth century

Transistor was invented and soon replaced

The diode and triode valves.

The diode and triode valves were used

Up to 1940sto construct the first calculators

No doubt theywere very efficient.

They could switch on or switch off currents

Millions of times in just one second.

But the valves were like small electric bulbs

Twenty thousand of these valves were required .

To make one calculator

Each valve had a hot filament .

Much heat developed and much current was wasted.

Dozens of the valves were damaged every hour.

The entire calculator stopped working

If any valves got damaged.

The machines were also unwieldy.

When the big valves were in use

A single calculator needed

A dozen steel cabinets

And a big air-conditioned hall!

The transistor was on the contrary

a small crystal of the size of a sand grain!

It was kept sealed in a metal casing

It had two long thin wires called “cat’s whiskers”

To lead small currents in and out.

Technologies soon developed

Very tiny transistor assemblies were made.

They were connected by “printed circuits”

The first generation of transistorized computers

Were sturdy and very efficient performers.

Thin wafer like transistor assemblies

With hundreds of thousand of transistors were made.

The CPU, the ALU and even the MAIN MEMORY

Were all constructed on a single “silicon chip”.

These are the famed “integrated circuits”

People started to use the word “computer chip”

The tiny size circuits were created on the chip

Using latest chemical technologies

And special computer programs.

These techniques are called LSI (large scale integration)

And VLSI (very large scale integration).

The main reward is the desk top or microcomputer

With “disk based operating system” the MSDOS.

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The cell phones and the new toys,

Automatic controls in cameras and TVs,

In Frigidaires, air conditioners and washing machines,

The auto pilots in cars, trains and planes,

And in the military weapons,

The brains of the robots,

And theelectronic meters of all kinds,

All these contain computer chips.

But remember the big fact

All this development is based

On the original “von Neumann plan”

Consisting of the main memory board,

The ALU,the CPU and the registers .

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