Information Communication Technology 10

The history of networks is a little confused, because the meaning of the word 'network' is being stretched a bit to cover everything people want it to mean, from a group of people to a bunch of wires. But, if we just take a technical point of view, then the invention of the telegraph was probably the first component.

In 1844 an American named Samuel Morse sent the first message by telegraph over a distance of 37 miles from Washington, DC to Baltimore. He had been working on this invention for 12 years, and it broke the electronic barrier of distance and time. For the first time in human history, a message could get somewhere faster than a person could transport it -- like instantly. Because of the telegraph, messages could now be turned into bits of information, sent, and reconstructed at their destination.

The telegraph was quite a crude device, just an on-or-off switch. All it really did was it sent an electrical blip down the line. It was like communicating by using the sound of a lamp shorting out. The really brilliant part of the telegraph was Morse Code, which took that single electrical blip and made it into a language.

Since all you had to work with was a blip, a longer blip, or nothing coming down the line, the trick was to represent every letter of the alphabet (and some punctuation) with a combination of short and long blips and use the silences as breaks between words. Skillful telegraph operators could send or receive dozens of words per minute, decoding the sounds by ear and encoding messages on the fly.

The other important thing about telegraphs was the system that evolved, the telegraph network itself, more than a million miles of wire by the year 1900, and the social connectedness it created. A variety of specific jobs developed to service the telegraph industry, from Morse code operators to telegram delivery boys. Older movies often feature references to the (then very common) culture of the telegraph.

The next historical network is still with us today. It's the telephone. You may have seen them around. Perhaps you've even used one.

It's a little difficult to appreciate the telephone fully, because it is such a major part of our society. It's so useful it's been an essential device for 100 years and it became a common household item about 50 years ago.

The telephone works great. Because so many people have phones, you can dial a few numbers and connect to anybody. The phone system basically consists of a lot of wires -- really a lot -- all leading to central switching stations, which connect my phone to yours when I dial your number. It's all very simple, in principle, although it's a fair bit more complicated in practice today. With cellular phones and satellite communications, you don't even have to be connected to a land line anymore.

Both the telegraph and telephone systems are analog networks -- they use good old fashioned sound to communicate. Computer networks, however, are digital networks. Telephone companies, especially AT&T, started changing their networks to digital systems in order to make automated dialing and switching more possible. We'll talk more about digital and analog in another lesson.

The first major use of digital networks was time-sharing on mainframes, brought about by advances in monitors and terminals that allowed people to work online relatively quickly -- well, quicker than with punch cards and teleprinters, anyway. Computers were so incredibly expensive that it was necessary to try to use them as efficiently as possible. So, while you were entering your program, somebody else was running theirs. And so it would go around. We are now familiar with the image of many green-screen terminals connected to a central mainframe. These were the first really important networks.

Computers used to be so scarce (in 1972 there were only about 150,000 in the world) people had to share them. But there are only 24 hours in a day, so booking them out in hourly blocks (like a meeting room gets booked) might not begin to cover the demand. Besides, that's a waste. Except for when it's actually doing a calculation, your average computer is bored to tears, or would be if it could cry. A computer spends most of its time waiting for humans to finish doing something: to finish typing, to finish reading, to finish printing. Waiting, waiting, waiting.