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unique combination of dots and or dashes, and both operators studied the code, memorized it and practiced using it. For instance, the code for the letter ‘N’ was dash dot (-.) and the code for the letter ‘C’ was dash dot dash dot (-.-.). The length of the on times were different to make dots and dashes, and the lengths of the off times were different to distinguish between the time that separates dots and dashes within a letter, the time that separates letters, and the time that separates words. You need a longer off time to keep from confusing a ‘C’ with two ‘N’s. The receiving person had to recognize these as patterns – that is, he had to hear and remember the lengths of several on and off times until he recognized a letter. The telegraph apparatus didn’t have any memory at all, there was never even one whole letter on the wire at any one time, the pieces of letters went down the wire, to be assembled into dots and dashes in the mind of the operator, then into letters, and then into words and sentences written on a sheet of paper. So the telegraph bit achieves more than two meanings by having several individual times when there may be ons or offs.
    If a computer were built on the principles of the Morse code, it would just have a light bulb on top of it flashing the code at us. Since we’d rather see whole letters, words and sentences on the screen simultaneously, we need something more than a single bit and this old code.
    Even in the examples used in this chapter, real traffic lights actually have three bits, one for red, one for yellow and one for green. If you had only one bit, you could just have a red light at the intersection, and when it was on that would mean stop, and when it was off that would mean go. But when it was off, you might wonder whether it was really off, or whether the bulb had just burned out. So using three bits is a lot more useful in this case.
    In the real world, we have already seen that computers can contain letters, words, sentences, entire books, as well as numbers, pictures, sounds and more. And yet, all of this does come down to nothing more than bits.
    If we want our computer memory to be able to hold more than an on or off, or yes or no, we will have to have something more than just one bit. Fortunately, we can do something much more useful just by using several bits together, and then making up a code (or maybe several codes) to assign some useful meaning to them.

 
    A Rose by Any Other Name
    Before we go on, we are going to introduce a change to what we call something. As we know, all of the bits in the computer are places where there is or is not, some electricity. We call these states, “on” and “off,” and that is exactly what they are. Even though these are short words, there are places where it is a lot easier, clearer and simpler to use a single symbol to describe these states. Fortunately, we’re not going to invent anything tricky, we’re just going to use two symbols you already know well, the numbers zero and one. From here on out, we will call off 0, and we will call on 1. And sometimes we will still use on and off.
    Thus the chart for our NAND gate will look like this:
     
 
      a
 
      b
 
      c
 
      0
 
      0
 
      1
 
      0
 
      1
 
      1
 
      1
 
      0
 
      1
 
      1
 
      1
 
      0
    This is very easy to understand, of course, but the point that needs to be made here, is that the computer parts have not changed, the only thing that has changed is what we, as people looking at the machine, are calling it. Just because we call a bit a zero or one, that doesn’t mean that suddenly numbers have appeared and are running around inside the computer. There are still no numbers (or words or sounds or pictures) in a computer, only bits, exactly as previously described. We could have called them plus and minus, yes and no, true and false, heads and tails, something and nothing, north and south, or even Bert and Ernie. But zero and