RTL8139C

The RTL8139C is a Realtek Semiconductor Corp. PCI Fast Ethernet controller and a revision in the RTL8139 family. It provides 10/100 Mbps Ethernet through a single-chip solution used in PCI-based computers and various embedded devices.

Technically, the RTL8139C integrates the MAC and PHY on a single die and uses a 32‑bit PCI bus interface with bus mastering. It supports IEEE 802.3 and 802.3u standards, auto-negotiation between 10BASE-T and 100BASE-TX, and operation in half- or full-duplex modes. The device presents a set of PCI configuration and status registers to manage transmit and receive operations and other controller functions.

Software support for the RTL8139C is broad, with drivers available across major operating systems. In Linux, drivers in the 8139too family provide support for RTL8139C devices; Windows drivers from Realtek and OEM vendors enable standard networking functionality; BSD variants include compatible support in their kernels.

Market context, the RTL8139C was released as part of the early 2000s RTL8139 family revisions to improve compatibility and stability over earlier models. It offered a practical, low-cost solution for 10/100 Mbps Ethernet in consumer PCs and assorted embedded hardware. In contemporary use, RTL8139C-based NICs are largely considered legacy hardware, but they may still appear in older systems or budget networking equipment.