Figure 8.10. There are six schematic symbols of logic gates in this figure. The first one has three inputs on the left although gates may have any number of inputs from 2 to some large number limited only by the ability of the manufacturer to make the chips. The three inputs come to a vertical line. At the top of the line there is another line extending to the right which is about half as long as the vertical one. At the bottom there is another line extending to the right the same distance as the one at the top. The ends of each of the horizontal lines are connected by an arc forming a semicircle to the right. The output comes off from the middle of the arc. This figure is labeled A N D.

There second gate looks the same as the A N D gate except where the output line comes off there is a small circle attached to the larger arc. The output line is attached to the right side of the circle.

In the third gate the three inputs come to an arc which has its center to the left so it forms a slightly concave line. At the top another arc begins going to the right and swings downward to the output point making about one eighth of a circle. At the bottom of the left arc another arc starts that starts to the right and swings up meting the other arc at the output point making about 1 eighth of a circle. The output line comes off of the points on the right where the two 1 eighth arcs meet. This gate is labeled O R.

The fourth gate looks similar to the O R gate but at the point where the two arcs meet on the right is a small circle with its left side touching the point made by the two arcs meeting. The output line comes off the right of the small circle. This gate is labeled N O R.

The fifth gate looks like an op amp with only one input. The left side of the triangle is vertical and the input comes to the middle of it. There is only one input. On the point of the triangle, at the right, is a small circle similar to other gates in this figure. The output comes off of the right side of the circle. This gate is labeled N O T.

The last gate looks like the O R gate but there is another arc to the left of the one that is connected to the other two arcs. This arc has the same radius of curvature but is not touching the main part of the gate made of the three arcs. There are only two inputs and they come to the detached arc on the left. The output is taken from the point on the right where the two arcs meet. This gate is labeled X O R.

End verbal description.
Go back.