Boxes and cans

Most ICs look like gray or black plastic boxes having protruding pins. Common configurations are single inline package (SIP), dual inline package (DIP) and flat- pack. Another package looks like a transistor with many leads. This is a metal-can package, at times called as TO package.

Not only an IC looks like a box or can; the schematic symbols for ICs are simple geometric shapes like triangles or rectangles. A component designator is written inside the polygon, and the wires emerging from it are labeled according to their specific functions. But circuit details are too complicated to be drawn in schematic diagrams. There is no point in rendering all the detail anyway; it would only confuse engineers and technicians, and make diagrams so large that they may cover a wall, or a football field, or state of Kansas.

So then an IC is a black box. The engineer or technician can forget its inner workings, just as you do not well upon what is happening inside your personal computer as you are using it. Even with simplicity of IC symbol, an apparatus by using many ICs can have nightmarish schematic diagrams, having dozens of wires running around as parallel lines so close together that you should run a pencil along them to keep a track of them.

                                        Figure--IC packages: SIP (A), DIP (B), flatpack (C), and metal can (D).