[[RF.Spice A/D]] comes with a very large "Parts Database" containing thousands of passive, active and virtual devices. Some of these parts are generic SPICE or XPICE parts such as the Resistor (R), the Capacitor (C) or the Generic NPN-Type Bipolar Junction Transistor (Q). Many of the database's parts are actual devices from particular semiconductor device manufacturers, such as the switching diode BA582 or the NPN-Type BJT, BFR193, both manufactured by Siemens.
The new [[RF.Spice A/D]] has adopted a terminology that differentiates between the terms "Part" and "Device". In this terminology, a "Part" is an instance of a "Device" that you insert in your circuit. Devices are stored in [[RF.Spice]]'s Parts Database. They have certain simulation models and symbols with a set of [[parameters]], which may have default values. Devices are saved in the database and remain unchanged unless you alter them using B2[[RF.Spice]]'s Device Editor. When you place a new part like a resistor R1 in your schematic, [[RF.Spice A/D]] indeed pulls the device type from the database and creates an instance of it with a default name and default parameter value(s). In this case, you have resistor R1 with a default value of 1K. You can change the name of your resistor or change its value to anything else. Now if you place a second resistor in your schematic, it will appear with the default name R2 and a default value of 1K. Your two resistors have the same device type, but they are two instances of the "Resistor" device given two different names and possibly two different values. You can change the names and values of your parts at any time and save them with your circuit project.
==Three Types of Device Models==