thumb|A CNR slot

Communications and networking riser (CNR) is a slot found on certain personal computer motherboards and used for specialized networking, audio, or telephony equipment. A motherboard manufacturer may choose to provide such functionality in any combination on a CNR card. CNR slots were once commonly found on Pentium III–class motherboards, but have since been phased out in favor of on-board or embedded components.

As with the audio/modem riser (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 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.

With the integration of components such as Ethernet and audio into the motherboard, the CNR slot is obsolete and not found on modern PC motherboards anymore.

See also

  • Mobile daughter card (MDC)
  • Communications management
  • GeoPort

References

  • CNR Specification 1.1
  • CNR slot pinout and signals at pinouts.ru