Communications and Networking Riser
Encyclopedia
Edge connector
An edge connector is the portion of a printed circuit board consisting of traces leading to the edge of the board that are intended to plug into a matching socket. The edge connector is a money-saving device because it only requires a single discrete female connector , and they also tend to be...
found on certain PC motherboards and used for specialized networking, audio, and telephony equipment. A motherboard manufacturer can choose to provide audio
Sound card
A sound card is an internal computer expansion card that facilitates the input and output of audio signals to and from a computer under control of computer programs. The term sound card is also applied to external audio interfaces that use software to generate sound, as opposed to using hardware...
, networking
Network card
A network interface controller is a computer hardware component that connects a computer to a computer network....
, or modem
Modem
A modem is a device that modulates an analog carrier signal to encode digital information, and also demodulates such a carrier signal to decode the transmitted information. The goal is to produce a signal that can be transmitted easily and decoded to reproduce the original digital data...
functionality in any combination on a CNR card. CNR slots were once commonly found on Pentium 4
Pentium 4
Pentium 4 was a line of single-core desktop and laptop central processing units , introduced by Intel on November 20, 2000 and shipped through August 8, 2008. They had a 7th-generation x86 microarchitecture, called NetBurst, which was the company's first all-new design since the introduction of the...
-class motherboards, but have since been phased out in favor of on-board or embedded components.
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 8-pin network interface, while Type B uses 16-pin Media Independent InterfaceMedia Independent Interface
The Media Independent Interface was originally defined as a standard interface used to connect a Fast Ethernet MAC-block to a PHY chip.The MII design has been extended to support reduced signals and increases speeds...
(MII) bus LAN interface. Both types carry USB
Universal Serial Bus
USB is an industry standard developed in the mid-1990s that defines the cables, connectors and protocols used in a bus for connection, communication and power supply between computers and electronic devices....
and AC'97 signals.
As with AMR
Audio/modem riser
The audio/modem riser, also known as an AMR slot, is a riser expansion slot found on the motherboards of some Pentium III, Pentium 4, Duron, and Athlon personal computers...
, CNR had the cost savings potential for manufacturers by removing analog I/O
Input/output
In computing, input/output, or I/O, refers to the communication between an information processing system , and the outside world, possibly a human, or another information processing system. Inputs are the signals or data received by the system, and outputs are the signals or data sent from it...
components from the motherboard. This allowed the manufacturer to only certify with the U.S. Federal Communications Commission
Federal Communications Commission
The Federal Communications Commission is an independent agency of the United States government, created, Congressional statute , and with the majority of its commissioners appointed by the current President. The FCC works towards six goals in the areas of broadband, competition, the spectrum, the...
(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
Advanced Communications Riser
The Advanced Communications Riser, or ACR, is a form factor and technical specification for PC motherboard expansion slots. It is meant as a supplement to PCI slots, a replacement for Audio/modem riser slots, and a competitor and alternative to Communications and Networking Riser ...
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. The same group also developed a physically smaller version, the MDC
Mobile Daughter Card
The Mobile Daughter Card, also known as an MDC or CDC , is a notebook version of the AMR slot on the motherboard of a notebook computer. It is designed to interface with special ethernet , modem or bluetooth cards.-Intel MDC specification 1.0:In 1999 Intel published a specification for Mobile...
.
History
Audio/modem riser
The audio/modem riser, also known as an AMR slot, is a riser expansion slot found on the motherboards of some Pentium III, Pentium 4, Duron, and Athlon personal computers...
(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
ASIC
ASIC may refer to:* Application-specific integrated circuit, an integrated circuit developed for a particular use, as opposed to a customised general-purpose device.* ASIC programming language, a dialect of BASIC...
), and was plug-and-play
Plug-and-play
In computing, plug and play is a term used to describe the characteristic of a computer bus, or device specification, which facilitates the discovery of a hardware component in a system, without the need for physical device configuration, or user intervention in resolving resource conflicts.Plug...
compatible. On some motherboards, a CNR slot replaced the last PCI
Peripheral Component Interconnect
Conventional PCI is a computer bus for attaching hardware devices in a computer...
slot, but most motherboard manufacturers engineered boards which allow the CNR and last PCI slot to share the same space.
As of 2007, with the integration of components such as Ethernet and audio into the motherboard, the CNR is obsolete, and is not found on the most recent full sized motherboards. It can still be found on smaller form-factor motherboards (like microATX) with lower end processors, where it continues to perform its original function.
See also
- Audio/modem riserAudio/modem riserThe audio/modem riser, also known as an AMR slot, is a riser expansion slot found on the motherboards of some Pentium III, Pentium 4, Duron, and Athlon personal computers...
(AMR), the original Audio/Modem Riser which CNR replaced. - Advanced Communications RiserAdvanced Communications RiserThe Advanced Communications Riser, or ACR, is a form factor and technical specification for PC motherboard expansion slots. It is meant as a supplement to PCI slots, a replacement for Audio/modem riser slots, and a competitor and alternative to Communications and Networking Riser ...
(ACR), a 3rd party solution to the CNR problem. - Mobile Daughter CardMobile Daughter CardThe Mobile Daughter Card, also known as an MDC or CDC , is a notebook version of the AMR slot on the motherboard of a notebook computer. It is designed to interface with special ethernet , modem or bluetooth cards.-Intel MDC specification 1.0:In 1999 Intel published a specification for Mobile...
(MDC), a version of ACR for mobile devices - GeoPortGeoPortGeoPort was a serial data system used on some models of the Apple Macintosh. GeoPort slightly modified the existing Mac serial port pins to allow the computer's internal sound hardware to emulate various devices such as modems and fax machines. GeoPort could be found on late-model m68k-based...
, a similar standard for the Apple Macintosh