Reading Logic Diagrams

Logic Diagrams DOE-HDBK-1016/2-93 TRUTH TABLES AND EXERCISES Rev. 0 Page 13 PR-05 Figure 12 Logic Gate Status Notation Reading Logic Diagrams When reading logic prints the reader usually must decide the input values to each gate. But occasionally the print will provide information as to the normal state of each logic gate. This is denoted by a symbol similar to the bistable symbol, as shown in Figure 12. The symbol is drawn so that the first part of the square wave indicates the normal state of the gate. The second part of the square wave indicates the off-normal state of the gate. Figure 12 also illustrates how this notation is applied. Reading a logic diagram that does not provide information on the status of the gates is not any more difficult. It simply requires the reader to choose the initial conditions, determine the response of the circuits, and modify the inputs as needed. The following exercises will illustrate how to read some simple logic diagrams. Examples To aid in understanding the material presented in this module, practice reading the following logic diagrams by answering the questions. The answers are on page 18.