Mr. Wizard—Peeking into the Dark Unknown

(1962, age 14)

Don Herbert was his real name, but everyone knew him as “Mr. Wizard.” Mr. Wizard showed me the wonder in the world. The way things worked—those were the mysteries for me. I could contemplate them safely, and work them through in the safety of my mind, without having to deal with people. I believe that I had a fairly ill-developed capability of dealing with people. I probably still do, but I’ll write about that later. Don Herbert was known on television and “Mr. Wizard.” For me, his shows were like peeking into the Dark Unknown and coming away with magical understanding. His shows are timeless, and are still shown on cable in syndication over 30 years after I first glued myself to my parent’s small black and white television screen.

I was strictly forbidden to watch any cartoons; the Howdy Doody show was very marginal as acceptable entertainment; Mr. Wizard was “approved” by my mother. She would later regret the decision, as Mr. Wizard encouraged me to tinker with the world around me—building things, tearning them down, rebuilding other things. Tinkering. I’ll never forget the incident years later, when I was in high school, when my mother pleading in frustration with my father to “Please stop him from tinkering!”

My first project was building an electric motor. Back in the 1950s, there were no stores like today’s Radio Shack, which has rows and rows of conveniently packaged electronic components. Whatever I built back then had to be made out of what I could buy at the hardware store. So from with a wooden frame and assorted nails and doorbell wire, I fashioned a crude electric motor. Once I connected the lantern battery and gave the armature a little shove, it kept turning on battery power. That I had taken pieces of something—nails, doorbell wire—and combined them in a way that did something completely different—that’s what hooked me.

There was something there, something unseeable. I had a vague idea of what an electron is. An electron can be thought of as a small packet of energy. There are lots of electrons piled up in a battery, just waiting for something to do. The way I connected the wires allowed the electrons to flow in a particular path, as as they made their journey, they created an electromagnetic field. A varying electromagnetic field interacting with a stationary one is what kept my little motor spinning. I had taken the power of the electron and converted it into my own use: motion.

Electromagnetic fields can do more than turn motors. They are the basis of radio and television communications; we are surrounded by electromagnetic fields every moment of our lives. Later I would be drawn into that world, but first I made a side trip which would prove prophetic. Time for a short lesson.

I just described how electromagnetic fields could turn the motor I had built. The field I created drew the metal of the motor’s turning armature toward the magnetic force, and just as the armature completed a half a revolution, a part of the motor known as the commutator reversed the current through the field and drew the armature around completing the rotation. That same mechanism of using electric current to draw a metallic thing is used in what is known as a relay. Relays, disguised in many forms, were critical to most of what I’ve done with my life in terms of technology. The “relays” I work with today are quite different.

SPDT relay

Here is a drawing of a relay. It has three main parts: a coil(6), an armature(8), and a set of contacts (10, 11 and 12) for switching electric current.

When electrons are passing through a relay coil, we say it is “energized” as shown on the right of the diagram. Passing current through a relay coil makes the relay armature draw against the coil, pushing the flexible metal contact (10) up, and in this energized position electrical contacts close, allowing current to flow from contact 10 to the upper contanct, 12. These contacts can carry other current, indicating that the relay is closed. Another set of contacts is used in the non-energized position: contacts 10 and 11. Thus we have a basic element of logic: a device which can have one of two conditions, or states.

Bear with me, as this is important. Not just to my story, but to you if you want to understand the world you live in a little better. What I’m going to explain is the basis of not only my tinkering in 1961, but of every computer that has been built since then. I know not what year this will be read in, but I suspect that long after I’m gone, what I discovered for myself in 1961 will remain the basis of computers and control systems. (For those in distant generations who will think “What an naive old coot Roger was!”, let me defend myself by saying that I have an inkling, I believe, of what major changes are coming long after I’m gone in this field, and that combinatorial and sequential logic will be obsolete for all but the most trivial of tasks.)

So pay attention as I give you perhaps the only technical lesson in this whole series of essays. There will be no test at the end of the chapter, but do try to follow along.

Let’s represent the relay contacts as a switch which, when closed, allows the flow of electric current. We’ll use a simple schematic representation of a switch. Let’s add a battery and a lamp bulb. Here are two circuits, one with the switch “open” and the other with the switch “closed.” In the closed switch example, current flows from the battery through the closed contacts of the switch, through the lamp bulb and back to the battery. The light bulb is lit when the switch is closed.

SPDT relay

This is how the light switch in the room you are in works. It’s a simple idea, but it’s the same idea that is the foundation of current computers. Let’s see how that can be. Let’s take two switches, or relay contacts, and connect them as in the following diagram.

logical AND with two switches and lamp

What does it take to light the lamp bulb? You’ll see the both switches must be closed for current to get to the light bulb from the battery. Thus Switch A and Switch B must be closed to complete the circuit. If these switches are really relay contacts, then energizing the coil of the relay with contacts “Switch A” and the coil of relay with contacts “Switch B” will cause the light to come on. We have created a logical circuit which implements the idea of “AND”. An example might be Relay A which is energized when an automobile’s ignition is turned on, and Relay B energized when the fuel tank is low on gasoline. Thus the “low fuel” indicator will turn on when both the ignition is turned on and the fuel remaining is low. We don’t want the light on while the car is not in use, so we use the and construction of the switches.

Another important combination is when the switches are arranged as shown in this diagram. What happens here? Can you figure out what “word” we are implementing? The light will be on if either Swicth A or Switch B is closed. Now, with relays or switches, we can construct…

logical OR with two switches and lamp

The “word” we were looking for is “OR.” Closing switch A or switch B lights the lamp. Used as a logic element, if “it is daytime” OR “nobody is home” then I should turn out the lights.

One more logic element and we’re done. Look back at the relay diagram. When current flows through the wire (2-3) and the armature is pulled in, an electrical path is made from (1) to (5). If no current is flowing, an electrical path is made from (1) to (4). This is the basis of the “NOT” logic element. No current in the coil allows current to flow from (1) to (4). Current in the coil does NOT allow current to flow from (1) to (4).

These operations are functionally complete. What this means is important. With just these three statements, AND, OR and NOT, I can readily construct all possible logical truth tables. Simply put, everything in a computer is represented by a signal that is on or off (binary), and combining these with a functionally complete logic set, like AND, OR, and NOT, is all that is needed for even the most complicated programs in the most powerful computers.

I built my first logic circuit with relays. Relay contacts, acting as switches, provided exactly what I needed. The problem it solved was the classic fox, goose, corn puzzle, in which a farmer must transport a fox, goose and bag of corn from one side of a river to another using a boat which can only hold one item in addition to the farmer, subject to the constraints that the fox cannot be left alone with the goose, and the goose cannot be left alone with the corn.

The relays were connected so their connections could detect such things as the fox AND the goose on one side of the river OR the goose AND the corn on one side of the river. Either of these conditions with NOT the farmer present to protect his animals or grain set off a buzzer.

A modern computer makes these decisions, not with relays or switches, but with microelectronic switches that steer current in exactly the same manner. It’s just that there are no moving parts. With the ability to combine AND, OR, and NOT functions and then to make decisions based on the logical results of those operations, entire programs can be written.

But now you have the basics, and so did I when I built that first relay “computer” in 1961. It could do only one thing because it’s “program” was wired literally with wires between relay coils and contacts. Computers which I was to design later used a stored but changeable program to make the decisions and control what the program did. Thus they were more flexible and much faster, making each decision in less than one millionth of a second. Yet the principle was unchanged.

It would be many years before I got back to computers. I was interested in everything to do with electronics, and technology didn’t exist for me to build a useful computer in 1961. So I explored many other pieces of electronic tecehnology. This included cathode ray tubes, which fascinated me, and the physics of semiconductors. I allude to some of these explorations in other essays. But it wasn’t until January of 1975 that my interests returned to computers, triggered by a magazine cover. I would work in that world for the following twenty-five years.