The arrival of the transistor. The Prehistory of Unix Part Four

The arrival of the transistor

This group of articles aims to tell the story of Unix, the operating system that paved the way for Linux, the open source derivatives of BSD, and indirectly macOS and Android. But to understand Unix you have to know the history of Bell Labs, AT & T's research division.

There must be very few cases in which a company invents an industry practically by itself. Automobiles, the computer industry or the manufacture of airplanes were the result of the investigations of multiple people in different places. Instead Bell Labs and its predecessors, the research branches of Western Electric and AT&T, developed almost everything needed to create a modern telephone network.

AT&T has its roots in the inventor of the telephone himself, Alexander Graham Bell. In the early days, things that we now take for granted like the ringing tone, the busy tone, the hook for hanging up the handset or the dial dial did not exist. It is said that if you wanted to make a call you had to shout and wait for someone who passed near the device to answer you.

About us I had to solve thousands of problems every day that no one had faced up to that moment. For that he created a group of multidisciplinary specialists that included engineers, chemists, physicists, mathematicians and specialists in metallurgy among others.. They not only had to keep the current system in working order but to prepare it for an increase in demand. Furthermore, in order to remain a monopoly, it had to lower costs.

There were two major obstacles to achieving these goals. Vacuum tubes (of which Speak in the previous articler and the reles.

A relay is an electrical switch that allows the electrical current to pass when it is closed and prevents it when it is open. The opening and closing of the switch is also done electronically.

The manufacturing of the vacuum tubes was a quasi-artisanal activity that required multiple steps and with very little tolerance to failures.. Once built they had a high consumption of electricity and generated a lot of heat. The relays, whose function was to ensure that calls reached their destination within the telephone network, tThey had multiple metal contacts that wore out. Also, its response time was slow.

Solid-state physics and the advent of the transistor

Solid state physics is dedicated to the study of the properties of materials and how they relate to their properties at the atomic scale.

Solid materials are formed from densely packed atoms, which interact intensely. These interactions produce the mechanical (eg, hardness and elasticity), thermal, electrical, magnetic, and optical properties.

In solid state devices electricity flows through solid semiconductor crystals (silicon, gallium arsenide, germanium) instead of through vacuum tubes.

If they could find the right materials, Bell Labs reduce costs, manufacturing time, and the life of the mechanisms used to route telephone calls and ensure signal quality.

In 1939 they began to study semiconductor materials. These materials are so named because they are not good conductors of electricity as is the case with copper) or good insulators of electricity such as glass. Another interesting property is that they only allow current to pass in one direction. All you had to do was find a material that would also amplify the sound.

The work was interrupted by World War II where the resources of Bell Laboratories were dedicated to military communications and the improvement of radar detection technologies.

Resuming their work, the scientists ran into a problem, semiconductor materials did not have amplification properties. This occurred because the upper part of the semiconductor material (they were using Germanium or Silicon) prevented the passage of current. They finally solved the problem by applying a conductive solution.

They then created a device made up of a small slice of semiconductor material about a quarter the size of a penny on a metal base. A wire was attached to the base while a small triangular piece of gold-wrapped plastic pointed toward the top face of the slice. At the tip there was a small, almost imperceptible incision creating two wires with a small separation.

That device would be the foundation of something known as a transistor and it would be the foundation of the electronics industry in the XNUMXs and XNUMXs. They would also allow the appearance of the second generation of electronic computers.


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