The PCS Software Modem Windows Driver is a driver for a software-based modem, sometimes called a "virtual" or "software modem." Unlike traditional hardware modems that have a dedicated physical chip to handle data transmission, software modems rely on your computer's processor (CPU) to manage the communication and modulate/demodulate the data for dial-up connections. These modems are often used in situations where a physical modem card isn't available or necessary, and they emulate modem functionality using software.

The term "PCS Software Modem" could refer to a specific brand or type of virtual modem. "PCS" could be the manufacturer or part of the name, but it's not a widely recognized or standardized term for modems. The exact device you're asking about may vary depending on the manufacturer or the specific modem technology used.