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Computer hardware implements the binary language of Module 6 using digital circuits. In this module, we provide you with a program called Logg-O, for designing and experimenting with simple digital logic circuits. It will be used to demonstrate the utility of logic for carrying out computations. | |
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| Module Quiz |
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The Module 6 labs demonstrated both the feasibility and the necessity of using a binary language as a means for communicating with a computer. Why, though, do computers understand only such simple languages? Because both binary numbers and a computer's hardware are essentially two-valued systems and, as such, can be used to represent and implement boolean logic. | |
In the text part of this module, we see how the computer, at the lowest level, is a physical embodiment of the rules of logic. Starting with simple switches, we build increasingly complex hardware - using switches to construct simple circuits, then using these to construct a hierarchy of more complicated circuits, or chips, and finally connecting these circuits to build a computer. By the end of this module, you will have constructed, on paper at least, a simple but fully functioning computer with nearly all the important features of real machines. | |
The metaphor for this module is the light switch, a box with a small lever and two wires attached. Flip the lever down and no current can flow through the wires; flip it up and current can pass. We won't worry about how things work inside the switch because for our purposes it is sufficient to assume that it does what we want. All we need to do to accomplish most of the mechanized computations we've described is remove the lever from the switch and replace it with an extra wire that can be used to control the switch. With enough of these switches, connected in the right way, we can implement any computer operation we want. |