CNR ACR

12/1/2000

Communications Network Riser (CNR). CNR is an (incompatible) successor to the Audio Modem Riser. CNR is being heavily hyped by Intel as of late 2000. Advanced Communications Riser (ACR) is a rival to CNR being pushed by an industry consortium. ACR is incompatible with CNR and uses a different connector than AMR.

AMR suffers from a number of problems. It lacks Network interfacing and displaces a PCI slot. It lacks a PNP compatible EPROM.

CNR is basically AMR plus either USB or Ethernet but not both. The design tends to integrate easily with Intel CPUs and chipsets. It is claimed that the CNR has been intentionally designed to impede the use of non-Intel chipsets. CNR does not displace a PCI slot. CNR is not compatible with the AMR. USB via CNR is intended to support ADSL or Wireless connections.

ACR is a superset of AMR run through a reversed PCI connector that could not hold a PCI card without major surgery. It is intended to work with both Intel and non-Intel components and chipsets although Intel claims otherwise because ACR does not support Intel's proprietary LAN Connect (LCI) connector and interface.

As with AMR, there is no intention that consumers will buy and install CNR or ACR components. The slots are intended to allow OEMs and large integrators to plug in communications solution. In particular they allow just the plug in module to be certified to local Telephone network standards instead of requiring certification of the motherboard. There is no requirement that motherboard support all CNR, AMR or ACR functions. Cards and motherboards must be engineered to work together.

CNR routes network connections through a single RJ45 or RJ11 connector. i.e. one modem or one Ethernet connection. Not both. As a result, CNR cards will come in at least two incompatible flavors (MII and LCI). [Note: This sounds exceptionally obtuse even for Intel.] ACR supports two ADSL or two Ethernet connections or one of each. ACR supports either MII, GPSI, or both. Neither ACR nor CNR addresses wireless communications unless the wireless implementation looks like an existing interface. Both support PNP EPROMs.

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