Schematic capture is the beginning of the process whereby a block diagram is converted into a pcb. Generally, schematic capture programs use a library which associates a graphical symbol with one or more part numbers (e.g. 1 kohm resistors of a certain form factor, but from different manufacturers); symbols from this library are placed on schematic sheets, and the schematic capture program provides a method for wiring these symbols together to create a functional circuit. The database is then passed to a layout program for parts placement and trace routing and finally a pcb artwork file is generated.
Common schematic capture programs include Protel, ViewLogic, and Mentor Graphics.