What is the difference between an internal and external modem?
A hardware (or real) modem has a controller and interfaces to a PC that outputs serial data through a COM port on a PC. The modem hardware then processes this data and converts this to analog for the phone line. The majority of this in an internal modem (or software modem) is done by the CPU and the resulting data is transferred through the modem card in a virtual COM port. These modems do not use a COM port, but since all modem application software is designed to use a COM port, the modem driver emulates a physical port (tricking the OS in the process) so that communications software applications will work (ie- Dial-Up Networking).
