Riser Cards

[ACR Riser CCA] [AMR Riser CCA] [CNR Riser CCA] [ATX Riser CCA]

Riser Card Description

There are three main Riser standards ACR [Advanced Communication Riser], AMR [Audio/Modem Riser], and CMR [Communication and Networking Riser]. Each Riser standard has a listing on this page which may provide additional technical information about the standard. The Riser approach is designed to bring the basic wiring and control of a function to a riser slot [and board] so the function may be implemented with minimal cost ~ with out the need for a PCI interface, for example. Computer OEM's [Original Equipment Manufacturers] would use a Riser slot [and board] to deliver a modem function at minimal cost. While a consumer would not up-grade using a Riser slot, opting for a PCI slot implementation instead. So Riser implementations are only seen as deliverables from computer manufacturers, and not as up-grade cards in commercial stores.

Reading the News groups it appears many people are surprised to find a riser slot and have no idea what it is for. Many see them as low cost cards using a slot that could have been a spare PCI slot. High end users or up-graders would rather see a PCI card using a PCI card slot. Opting for the expansion card performing the work instead of the cpu using/wasting cpu cycles. However; many people are more concerned about cost with out regard for the number of PCI expansion slots, or whether the function is performed by the processor or some expansion card.

ACR Riser Bus Description

Advanced Communication Riser, another Computer OEM Riser specification. This latest version provides for modem support, LAN and xDSL support, and Audio support. ACR was preceded by CNR and AMR, both listed on this page. The ACR standard is backwards compatible with AMR. Additional description of Riser cards is also listed below. Also, the ACR standard may be in competition with the CNR standard.

AMR Riser Bus Description

Audio/Modem Riser specification defines a hardware scalable OEM PC mother board riser card and interface, which supports both audio and modem functions. An MR slot will provide a Modem function, while a AMR slot will provide both an Audio and Modem function. The modem is a WinModem.

CNR Riser Bus Description

Communication and Networking Riser: The Specification defines a hardware scalable Original Equipment Manufacturer (OEM) mother board riser and interface that supports the audio, modem, and local area network (LAN) interfaces of core logic chipsets. This standard does not support an expansion slot, but an OEM built in board to include the Motherboard connector [CNR Connector]. Supported interface buses include, AC '97, SMBus and USB including Power and a LAN interface. The board size and pinout are also defined in the specification for the ATX series of motherboard form factor.. It appears Intel no longer produces CNR slots on its Pentium 4 Processor based Motherboards. The pinout for both the Type 'A' and Type 'B' connector are listed on the CNR Riser Card Pinout.

ATX Riser Card

Riser card used with ATX form factor mother boards. The description and pin out has moved to the ATX Riser Card page.

PCI Riser Card Manufacturer; Hartmann Elektronik {PCI Riser Card, 5 V, 32-bit - 2 Slot passive}

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AT Form Card Description

The AT Form Card is used on the old original AT Motherboards. The AT Form Card was designed to up-grade the old AT form Factor motherboard to allow for ATX connectors. This turned out into translating a dual-pin header located on the mother board into a connector on the rear I/O panel.
The AT Form Card page provides the pinout for this interface.

{PC Riser Bus Index}

EATX Riser Card Description

The Extended ATX motherboard uses an HTX riser card based on HyperTransport.

Riser Card IC Manufacturers

The Riser board standards listed here use standard PC IC's. The actual IC chip interface will depend on the bus interfacing to the Riser board.
Refer to the PC Interface Bus page for a complete listing of computer buses. In most cases driver IC's will be listed on one of those pages.
For all other IC functions use the Components Icon below.

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PC motherboard

Distributor rolodex Electronic Components Electronic Equipment EDA CDROM Software Engineering Standards, BOB card Cabled Computer Bus Electronic Engineering Design Table Conversion DB9-to-DB25.
DistributorsComponents Equipment Software Standards Buses Design Reference

Modified: 3/05/12
Copyright © 1998 - 2016 All rights reserved Larry Davis