CNR/AMR ? What do these mean?

[Arjay13]

I've seen CNR (I think) and ANR mentioned with regard to motherboards. What are they and how do you use them? Thanks in advance.

[Tomteriffic]

CNR and AMR are small slots on a motherboard that support small riser cards, typically for modems and/or network cards. CNR stands for "Communications/Networking Riser". AMR stands for "Audio/Modem Riser".

Typically these are used for either 56K winmodems or ethernet adapters. They're also typically pretty low-grade, but serviceable.

If the motherboard you're considering doesn't ship with the riser card, and you had designs on using the riser card, ferget it. They're pretty hard to come by and generally not worht the effort.

In short, it's a symptom of the move toward greater integration on motherboards.

OH, and an AMR riser card won't work in a CNR slot and vice versa.

[Peter M]

ECS Elitegroup and PC-Chips (same company anyway) actually do ship AMR or CNR modems with their all-in-one boards, and they also have the cards for sale separately (at least the ECS web shop here in Germany does).

Not having LAN and modem components physical interface onboard is more about not having to make country specific mainboards (phone line interfaces differ greatly), and about last minute decisions on prebuilt systems. Like when the customer decide they want HomePNA networking not 10/100TX, you just plug the CNR HomePNA interface card in instead of the 10/100TX and there you go.
AMR cards are modem-only, CNR cards can have modem and/or LAN. Whatever, they just contain the physical interface, the actual job is done by some active component on the mainboard (like a chipset integrated LAN MAC or modem engine) ... much like chipset integrated sound where the chipset engine does the work and a separate codec does the analog interfacing.

The evolving ACR slot definition will make this all even more flexible (for OEMs of course, not for us end users), adding DSL to the game.

regards, Peter

[Arjay13]

Thanks very much for your replies!