The PCI Fast Ethernet DEC 21140 Based Adapter is a network interface card (NIC) that provides a wired Ethernet connection to a computer or device. The DEC 21140 chipset was developed by Digital Equipment Corporation (DEC), which later became part of Intel. This adapter supports 10/100 Mbps Ethernet connections, allowing your computer to connect to local area networks (LANs) at fast speeds.

To use the PCI Fast Ethernet DEC 21140 adapter in Windows, you need the appropriate device driver, which allows the operating system to communicate with the hardware. Without the driver, the system may not recognize the network adapter, or it may function with limited features.