MAC Configuration Register
| PRELEN | Preamble Length for Transmit Frames |
| RE | Receiver Enable |
| TE | Transmitter Enable |
| DC | Deferral Check |
| BL | Back-Off Limit |
| ACS | Automatic Pad or CRC Stripping |
| DR | Disable Retry |
| IPC | Checksum Offload |
| DM | Duplex Mode |
| LM | Loopback Mode |
| DO | Disable Receive Own |
| FES | Speed |
| DCRS | Disable Carrier Sense During Transmission |
| IFG | Inter-Frame Gap |
| JE | Jumbo Frame Enable |
| BE | Frame Burst Enable |
| JD | Jabber Disable |
| WD | Watchdog Disable |
| TC | Transmit Configuration in RMII |
| CST | CRC Stripping of Type Frames |
| TWOKPE | IEEE 802.3as support for 2K packets Enable |
| SARC | Source Address Insertion or Replacement Control |