Communications and networking riser

Technology

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 an 8-pin PHY interface, while Type B uses a 17-pin media-independent interface (MII) bus LAN interface. Both types carry USB and AC'97 signals.

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.

History

Intel developed the CNR slot to replace its own AMR technology, drawing on two distinct advantages over the AMR slot it replaced. CNR was both capable of being either software based (CPU-controlled) or hardware accelerated (dedicated ASIC), and was plug-and-play compatible.

With the integration of components such as Ethernet and audio into the motherboard, the CNR slot is obsolete and not found on modern PC motherboards anymore.

References

References

1. Staff writer. (June 12, 2000). "Intel Introduces New Chipset for Intel Pentium III Processor-based Performance PCs". Millin Publishing.
2. Rosch, Winn L.. (2003). "Winn L. Rosch Hardware Bible". Que.
3. Quentin, Docter. (2012). "CompTIA A+ Complete Deluxe Study Guide Recommended Courseware: Exams 220-801 and 220-802". Wiley.
4. Mueller, Scott. (2004). "Upgrading and Repairing Laptops". Que.
5. Prowse, David. (2014). "Computer Structure and Logic". Pearson.