{{unreferenced, date=June 2009, bot=yes ACP-Bus @ ASUS A7V266

The Advanced Communications Riser, or ACR, is a form factor and technical specification for

PC motherboard A motherboard (also called mainboard, main circuit board, mb, mboard, backplane board, base board, system board, logic board (only in Apple computers) or mobo) is the main printed circuit board (PCB) in general-purpose computers and other expand ...

expansion slot Expansion may refer to: Arts, entertainment and media * ''L'Expansion'', a French monthly business magazine * ''Expansion'' (album), by American jazz pianist Dave Burrell, released in 2004 * ''Expansions'' (McCoy Tyner album), 1970 * ''Expansio ...

s. It is meant as a supplement to

PCI PCI may refer to: Business and economics * Payment card industry, businesses associated with debit, credit, and other payment cards ** Payment Card Industry Data Security Standard, a set of security requirements for credit card processors * Pro ...

slots, a replacement for the original

Audio/modem riser The audio/modem riser (AMR) is a riser card, riser expansion slot found on the motherboards of some Pentium (brand), Pentium III, Pentium 4, Duron, and Athlon personal computers. It was designed by Intel to interface with chipsets and provide an ...

(AMR) slots, and a competitor and alternative to Intel's

communications and networking riser Communications and networking riser (CNR) is a slot found on certain PC motherboards and used for specialized networking, audio, and telephony equipment. A motherboard manufacturer can choose to provide audio, networking, or modem functionality in ...

(CNR) slots.

Technology

The ACR specification provides a lower cost method to connect certain

expansion card In computing, an expansion card (also called an expansion board, adapter card, peripheral card or accessory card) is a printed circuit board that can be inserted into an electrical connector, or expansion slot (also referred to as a bus slo ...

s to a

computer A computer is a machine that can be programmed to Execution (computing), carry out sequences of arithmetic or logical operations (computation) automatically. Modern digital electronic computers can perform generic sets of operations known as C ...

, with an emphasis on audio and communications devices.

Sound card A sound card (also known as an audio card) is an internal expansion card that provides input and output of audio signals to and from a computer under the control of computer programs. The term ''sound card'' is also applied to external audio i ...

s and

modem A modulator-demodulator or modem is a computer hardware device that converts data from a digital format into a format suitable for an analog transmission medium such as telephone or radio. A modem transmits data by Modulation#Digital modulati ...

s are the most common devices to use the specification. ACR and other

riser card A Riser Card is a printed circuit board that gives a computer motherboard the option for additional expansion cards to be added to the computer. Usage Risers is usually connected to the mainboard's slot through an edge connector, though some, s ...

s lower hardware costs by offloading much of the computing tasks of the

peripheral A peripheral or peripheral device is an auxiliary device used to put information into and get information out of a computer. The term ''peripheral device'' refers to all hardware components that are attached to a computer and are controlled by the ...

to the

CPU A central processing unit (CPU), also called a central processor, main processor or just processor, is the electronic circuitry that executes instructions comprising a computer program. The CPU performs basic arithmetic, logic, controlling, and ...

. ACR uses a 120 pin PCI connector which is reversed and offset, retaining

backward compatibility Backward compatibility (sometimes known as backwards compatibility) is a property of an operating system, product, or technology that allows for interoperability with an older legacy system, or with input designed for such a system, especially i ...

with 46 pin AMR cards while including support for newer technologies. It is also more cost-effective and simple for the manufacturer, since the connectors are identical to the PCI connectors already purchased in quantity. New features supported by ACR include standards for an

EEPROM EEPROM (also called E2PROM) stands for electrically erasable programmable read-only memory and is a type of non-volatile memory used in computers, usually integrated in microcontrollers such as smart cards and remote keyless systems, or as a ...

for storing model and vendor information,

USB Universal Serial Bus (USB) is an industry standard that establishes specifications for cables, connectors and protocols for connection, communication and power supply (interfacing) between computers, peripherals and other computers. A broad v ...

support, and the ''Integrated Packet Bus'' for

digital subscriber line Digital subscriber line (DSL; originally digital subscriber loop) is a family of technologies that are used to transmit digital data over telephone lines. In telecommunications marketing, the term DSL is widely understood to mean asymmetric di ...

(DSL),

cable modem A cable modem is a type of network bridge that provides bi-directional data communication via radio frequency channels on a hybrid fibre-coaxial (HFC), radio frequency over glass (RFoG) and coaxial cable infrastructure. Cable modems are primaril ...

, and

wireless network A wireless network is a computer network that uses wireless data connections between network nodes. Wireless networking is a method by which homes, telecommunications networks and business installations avoid the costly process of introducing c ...

ing support.

History

The ACR specification was created by the ''Advanced Communications Riser Special Interest Group'' (ACR SIG) in 2000 with the intent to replace the AMR specification. Because it was backwards compatible with AMR cards, and technically superior, it quickly replaced it. ACR is rendered obsolete by discrete components mounted on the motherboard.

Technology

History

See also