Systems, methods, and apparatuses including a Physical layer (PHY) block coupled to a Media Access Control layer (MAC) block via a PHY/MAC interface. Each of the PHY and MAC blocks include a plurality of Physical Interface for PCI Express (PIPE) registers. The PHY/MAC interface includes a low pin count PIPE interface comprising a small set of wires coupled between the PHY block and the MAC block. The low pin count PIPE interface is configured to transfer register commands between the PHY and MAC blocks over the small set of wires in a time-multiplexed manner to support read and write access of the PHY and MAC PIPE registers. The PHY block may also be selectively configurable to implement a PIPE architecture when operating in a PIPE mode and a serialization and deserialization (SERDES) architecture when operating in a SERDES mode.