Tuesday, November 26, 2013

Why Electronics Took Over the World


How did we end up in a world where computers are everywhere?

Originally, we had vacuum tubes as electronic components. Each of these has to be hand-made. When you consider that even the most basic computer, about the power of a programmable calculator, requires about 4000 electronic switches in it (including some basic control, memory, and interface circuits), you can see that needing 4000 hand made parts is going to get expensive. And that's before you wire them together into a working computer. It's like having to hire a team of scribes every time you want to get a new book.

Each of those tubes is like a decorated capital drawn by a scribe.

Transistors were a big step forward. Transistors aren't made one at a time by hand. Packaging them involved some hand work back when they were new, but the guts of them were produced en masse. Making transistors was like printing a sheet covered in letter "B" so that you could cut them up to have a letter B to stick wherever you need one. Similarly, transistors are made in a large group, which is then cut up into individual transistors then packaged for use.

So why not print the equivalent of a small piece of often-used text, rather than cutting it up into individual letters? This is the basis of the integrated circuit. It was another step forward in reducing the cost of electronics manufacturing. The first circuits were like having commonly used words, in complexity. Over time, technology advanced to allow more and more sophisticated circuits.


Eventually the circuits got more and more complex, and more useful. Building a computer got to be about as complex as creating a book on a typewriter. That means it took patience, and skill, and it was still expensive, but not nearly as expensive as hiring a team of scribes.

Each integrated circuit has from a few to as many as a few hundred transistors on it at this point. Building a basic computer circuit could be accomplished with a couple of hundred ICs.

The next step was a big one. Integrating the entire guts of a computer onto a single die, then printing them not one at a time, but by the tens then the hundreds at a time.

In the mid 1970s enough transistors were printed together, in the right circuits, to make a basic computer. When added to some memory (which was another technology that had recently benefited from the improvements in integrated circuits), a few ICs for control and for interfacing to the outside world, a complete computer could be built out of a handful of integrated circuits. Like my MAG-85 computer project, which uses about 10 ICs to build a basic 70's style computer.

But that wasn't enough. It was enough for calculators and very simple computers that require someone with a high level of skills to get the most out of them. If we'd stopped there, only very technical or very driven people would have computers. We had to increase their complexity to make them more capable, and easier to use.

Since then, we've improved our "printing processes" to allow us to produce integrated circuits that contain not just a few thousand "switches", but billions. Your computer, cell phone, or tablet contains the equivalent of billions of vacuum tubes. And yet, those billions of sub-microscopic electronic switches all together require less electrical power to operate than one single vacuum tube. They also generate less heat.

If we put the entire world population to work building electron tubes as fast as they can, we couldn't produce enough tubes to reproduce the computing power of a single cell phone in a year. In part because we couldn't build tubes that can switch as quickly as the transistors in a cell phone.
the guts of a simple vacuum tube
Imagine building a few billion of these, by hand. Image courtesy RJB1.
But the computer in the heart of that cell phone is one chip that was printed alongside hundreds of others just like it in a mass production process that's very similar to printing. Many of today's computer chips literally cost less to make than a printed magazine or book. Far less, usually.

This triumph of manufacturing, reducing electronics to a simple, inexpensive, high volume printing process, is why we have computers everywhere from our cell phones to our irons and dishwashers. They're cheaper to build than the parts they replace.

Have a look at a current computer chip sometime. Inside it are several billion man-made structures. You could look at them with a microscope if the top were removed, but you would only see patterns, not individual elements. The individual elements are too small to see in visible light now.
There are several billion man-made things in this image.

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