The Intel 21140-based 10100 Mbps Ethernet Controller is a network interface card (NIC) that uses the Intel 21140 chipset (also referred to as the DEC 21140 chipset when it was originally developed by Digital Equipment Corporation, which was later acquired by Intel). This chipset supports Fast Ethernet (100 Mbps), making it a popular choice for network connectivity in older systems.

The Intel 21140-based Ethernet controller typically uses a PCI interface, meaning it connects to a computer via a PCI slot. This driver is needed to enable the operating system (like Windows) to communicate with the Ethernet hardware and facilitate network connectivity.