In this tutorial you will use generic inverter gates and two-input NAND gates to build two-input and three-input AND circuits. You will learn how to define digital inputs and outputs and use [[RF.Spice]]'s live digital timing diagrams. It is assumed that by this time you have already completed the first few analog tutorial lessons and are comfortable with navigating the [[RF.Spice A/D]] Workshop.
=== Placing Digital Parts ===
To build your first digital circuit, you need the following parts:
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=== Defining Inputs/Outputs & Connecting the Parts ===
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[[File:b2TUT4_4.png|thumb|300px|Digital Input Dialog]]
[[File:b2TUT4_6.png|thumb|300px|Digital Output Dialog]]
{{Note|Unlike analog and mixed-mode circuits that are excited using voltage or current sources, digital circuits require "'''Digital Input Ports'''" which can only take either binary or hexadecimal data.}}
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Digital input and output ports are generic and virtual parts. You can get them from the "'''Digital I/O'''" submenu of the the "'''Parts Menu'''". Or you can easily place them in your circuit by typing the keyboard shortcut "'''N'''" for '''Digital Input''' and the keyboard shortcut "'''O'''" for '''Digital Output'''. Use the keyboard shortcut "N" to place your first input port to the left of the NAND gate. Then press the keyboard's "'''SPACE'''" bar to "Repeat Place Device" and place your second input port and repeat one more time to define the third input. Next, use the keyboard shortcut "O" to place your output port to the right of the inverter gate.
{{Note|In analog and mixed-mode circuits, you measure node voltages and device currents. In digital circuits, you probe only binary or hexadecimal data at "'''Digital Output Ports'''".}}
Digital input and output ports are generic and virtual parts. You can get them from the "'''Digital I/O'''" submenu of the "'''Parts Menu'''". Or you can easily place them in your circuit by typing the keyboard shortcut {{key|N}} for '''Digital Input''' and the keyboard shortcut {{key|O}} for '''Digital Output'''. Similar to all other parts or devicedevices, digital input and output ports have property dialogs that can be accessed by double-clicking on them. The figure below shows the property dialog of the digital input and output, respectively. By default, the digital input and output takes 1-bit binary data in decimal format (rather then hexadecimal).The keyboard shortcut for the NAND gate is {{key|Alt+A}}, and keyboard shortcut for the inverter gate is {{key|Alt+O}}. {{Note|You can use the keyboard's {{key|Space}} bar to "Repeat Place Device".}}  <table><tr><td> [[File:b2TUT4_4.png|thumb|360px|Digital Input Dialog.]] </td><td> [[File:b2TUT4_6.png|thumb|360px|Digital Output Dialog.]] </td></tr></table>Â
Your circuit at this point should like the figure below: