CNR

      Communications and Networking Riser

                            CNR

 

                                          

CNR slot

        Communications and Networking Riser (CNR) is a slot found on certain PC motherboards and used for specialized networking, audio, and telephony equipment. A motherboard manufacturer can choose to provide audio, networking, or modem functionality in any combination on a CNR card. CNR slots were once commonly found on Pentium 4-class motherboards, but have since been phased out in favour of on-board or embedded components.

        Physically, a CNR slot has two rows of 30 pins, with two possible pin configurations: Type A and Type B, each with different pin assignments. CNR Type A uses 8-pin network interface, while Type B uses 16-pin Media Independent Interface (MII) bus LAN interface. Both types carry USB and AC'97 signals.

As with AMR, CNR had the cost savings potential for manufacturers by removing analog I/O components from the motherboard. This allowed the manufacturer to only certify with the U.S. Federal Communications Commission (FCC) for the CNR card, and not the entire motherboard. This resulted in a quicker production-to-market time for new motherboards, and allowed mass-production of CNR cards to be used on multiple motherboards.

The ACR slot was a competing specification developed by a group of third-party vendors. Its principal advantage over CNR was the backwards-compatible slot layout which allowed it to use both AMR and ACR cards.

Modem CNR

Audio/modem riser -AMR

Advanced Communications Riser-ACR