riser card

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riser card

(1) A printed circuit board for low-profile motherboards. The peripheral controller cards plug into the riser card and sit parallel with the motherboard. See low-profile motherboard.

(2) An expansion card that is used to physically extend a slot in order to make it easier to plug in the chip or card.

(3) A small PC expansion card that contains audio, modem and networking capabilities. When first introduced, it let manufacturers create custom systems for different audiences using motherboards that had none of these built-in functions. After audio and networking were built into the motherboard, risers were used for modems because they could be easily interchanged for international certification (homologation). See AC'97 and HD Audio.

Audio/Modem Riser (AMR)
AC'97 Audio, V.92 Modem
In 1998, Intel introduced software-driven audio and modem capabilities in the 46-pin AMR card as well as a Mobile Daughter Card (MDC) for portable solutions. Although motherboards were built with AMR slots, AMR offered little because it usurped a PCI connection, lacked Plug and Play and was software driven.

Communications and Networking Riser (CNR)
AC'97, V.92, Ethernet, HomePNA, USB
In 2000, Intel introduced the 30-pin CNR card, which added Plug and Play support and audio, modem and network functions. CNR included USB and took up one PCI slot. Ethernet and HomePNA connectivity was provided via the Intel LAN Connect Interface (LCI) or the Media Independent Interface (MIL).

Advanced Communications Riser (ACR)
AC'97, V.92, Ethernet, HomePNA, DSL
In 2000, AMD, 3Com and others introduced ACR to supersede AMR. Taking up one PCI slot, it accelerated audio and modem functions in hardware. For audio and modem only, it could be built with a connector to plug into an AMR slot. For networking, the card used a full PCI slot, colored blue and reversed.

ACR allowed modem, HomePNA and DSL to be connected over one telephone jack. It also supported multiple Ethernet controllers.

PC Motherboard Riser Cards
ACR cards can be designed to fit into AMR slots or PCI slots (blue and reverse from standard PCI).
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References in periodicals archive ?
If a server only requires PCIe connectivity, then the problem of limited I/O expansion can be solved by placing a PCIe switch on the riser card, as in Figure 3.
GVC, Puretek, Wellcom, and Pineview will deploy ESS's modem technology into desktop PCs as a PCI riser card, while Ambit and Actiontec will provide ESS softmodem mini-PCI modules to top-tier OEM customers in the United States, including Hewlett-Packard and Dell Computers.
The RMC6224, utilizes an Intel[R] Xeon E3 Quad Core processor with Intel[R] C224 chipset on an industrial Micro ATX motherboard and features a built-in riser card with four low profile PCIe slots for expansion.
The board also has a special mining mode that runs the PCIe lanes at gen 1 speeds to improve stability and compatibility with riser cards.
Two new 280-position vertical card edge connectors enable the implementation of high-speed, serial PCI Express signaling to riser cards in rack-mount servers.
"Historically memory has been installed horizontally on two riser cards," explained Jeff Goldenbaum, Dataram's Product Manager.
Smart Link V.92 modem chipsets is available in several different form factors, including: PCI and Riser Cards targeted at PC OEMs; and USB targeted at the retail market.
Stye's packaging features riser cards that allow the product to be placed on J-hooks or pegboards as well as on shelves.
They are also narrow enough to fit all 2U rack mount systems without using riser cards. Quatech's serial Low Profile PCI line leverages the company's PCI expertise to provide the same features found in their standard PCI boards, such as four-layer board design fo r improved signal integrity, shared interrupts, 16-byte FIFOs and enhanced board speeds of up to 921.6 kbps.