# Truth Table Editor and State Table Editor

Truth tables state for each input configuration the corresponding output configuration. State tables are similar to truth tables except there is the concept of an internal state. State tables give the output values and next state for each configuration of input values and initial state.

On invoking the truth table or state table editors a dialog box requests the number of input pins, output pins and in the case of the state table editor, the number of internal states, for the chip. Once these values have been selected press continue and the editor window will appear with all of the input-state combinations already input.

To change output values, simply click on the respective cell. Clicking on cells toggles the value, so a '0' changes to a '1' and a '1' to a '0'. To change the value for the next state click on the respective cell and a combo-box containing all valid next states will appear. Click on the correct state in the combo-box. Note that states are given in decimal (base 10) values.

When the chip is placed on the breadboard a panel on the left states the label for each pin. To change pin labels in the table editors so that the correct label is shown in the breadboard simulator double-click on the table column headers. This will bring up an input dialog box into which the pin label should be typed.

The state table editor has an additional panel on the right-hand side for giving the chip's initial state in which it will start on power-up. When circuits are developed in hardware components which have state normally start in a random state so it must be remembered that when any circuits are translated from these tools into hardware that additional circuitry may be needed to force the initial state.

The properties panel at the bottom of the editor should be used for setting additional chip characteristics. For help on the components of the properties panel click here.

Once the chip table has been completed the chip file is saved by clicking File -> Create Chip File. Doing so brings up a save dialog box. Select the directory and filename and click Save. The file extension ".chp" will automatically be added. In order to create chip files loading and saving must have been enabled. Click here for more information.

Once the file has been saved the option is given to close the editor. Remember that once the editor has been closed the chip cannot be re-loaded into the editor and any changes will need to be made manually to the chip file. Thus it is advisable to test the chip in the breadboard simulator before closing the table editor.

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