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The Advanced Communications Riser, or ACR, is a form factor and technical specification for PC motherboard expansion slots. [1] It is meant as a supplement to PCI slots, a replacement for the original Audio/modem riser (AMR) slots, and a competitor and alternative to Intel's communications and networking riser (CNR) slots.
The ACR specification provides a lower cost method to connect certain expansion cards to a computer, with an emphasis on audio and communications devices. Sound cards and modems are the most common devices to use the specification. ACR and other riser cards lower hardware costs by offloading much of the computing tasks of the peripheral to the CPU.
ACR uses a 120 pin PCI connector which is reversed and offset, retaining backward compatibility 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 for storing model and vendor information, USB support, and the Integrated Packet Bus for digital subscriber line (DSL), cable modem, and wireless networking support.
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. [1] 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.
Accelerated Graphics Port (AGP) is a parallel expansion card standard, designed for attaching a video card to a computer system to assist in the acceleration of 3D computer graphics. It was originally designed as a successor to PCI-type connections for video cards. Since 2004, AGP was progressively phased out in favor of PCI Express (PCIe), which is serial, as opposed to parallel; by mid-2008, PCI Express cards dominated the market and only a few AGP models were available, with GPU manufacturers and add-in board partners eventually dropping support for the interface in favor of PCI Express.
A backplane or backplane system is a group of electrical connectors in parallel with each other, so that each pin of each connector is linked to the same relative pin of all the other connectors, forming a computer bus. It is used to connect several printed circuit boards together to make up a complete computer system. Backplanes commonly use a printed circuit board, but wire-wrapped backplanes have also been used in minicomputers and high-reliability applications.
Industry Standard Architecture (ISA) is the 16-bit internal bus of IBM PC/AT and similar computers based on the Intel 80286 and its immediate successors during the 1980s. The bus was (largely) backward compatible with the 8-bit bus of the 8088-based IBM PC, including the IBM PC/XT as well as IBM PC compatibles.
A motherboard is the main printed circuit board (PCB) in general-purpose computers and other expandable systems. It holds and allows communication between many of the crucial electronic components of a system, such as the central processing unit (CPU) and memory, and provides connectors for other peripherals. Unlike a backplane, a motherboard usually contains significant sub-systems, such as the central processor, the chipset's input/output and memory controllers, interface connectors, and other components integrated for general use.
Peripheral Component Interconnect (PCI) is a local computer bus for attaching hardware devices in a computer and is part of the PCI Local Bus standard. The PCI bus supports the functions found on a processor bus but in a standardized format that is independent of any given processor's native bus. Devices connected to the PCI bus appear to a bus master to be connected directly to its own bus and are assigned addresses in the processor's address space. It is a parallel bus, synchronous to a single bus clock. Attached devices can take either the form of an integrated circuit fitted onto the motherboard or an expansion card that fits into a slot. The PCI Local Bus was first implemented in IBM PC compatibles, where it displaced the combination of several slow Industry Standard Architecture (ISA) slots and one fast VESA Local Bus (VLB) slot as the bus configuration. It has subsequently been adopted for other computer types. Typical PCI cards used in PCs include: network cards, sound cards, modems, extra ports such as Universal Serial Bus (USB) or serial, TV tuner cards and hard disk drive host adapters. PCI video cards replaced ISA and VLB cards until rising bandwidth needs outgrew the abilities of PCI. The preferred interface for video cards then became Accelerated Graphics Port (AGP), a superset of PCI, before giving way to PCI Express.
The VESA Local Bus is a short-lived expansion bus introduced during the i486 generation of x86 IBM-compatible personal computers. Created by VESA, the VESA Local Bus worked alongside the then-dominant ISA bus to provide a standardized high-speed conduit intended primarily to accelerate video (graphics) operations. VLB provides a standardized fast path that add-in (video) card makers could tap for greatly accelerated memory-mapped I/O and DMA, while still using the familiar ISA bus to handle basic device duties such as interrupts and port-mapped I/O. Some high-end 386DX motherboards also had a VL-Bus slot.
PC Card is a parallel peripheral interface for laptop computers and PDAs. The Personal Computer Memory Card International Association (PCMCIA) originally introduced the 16-bit ISA-based PCMCIA Card in 1990, but renamed it to PC Card in March 1995 to avoid confusion with the name of the organization. The CardBus PC Card was introduced as a 32-bit version of the original PC Card, based on the PCI specification. The card slots are backward compatible for the original 16-bit card, older slots are not forward compatible with newer cards.
In computing, an expansion card is a printed circuit board that can be inserted into an electrical connector, or expansion slot on a computer's motherboard to add functionality to a computer system. Sometimes the design of the computer's case and motherboard involves placing most of these slots onto a separate, removable card. Typically such cards are referred to as a riser card in part because they project upward from the board and allow expansion cards to be placed above and parallel to the motherboard.
PCI Express, officially abbreviated as PCIe or PCI-e, is a high-speed serial computer expansion bus standard, designed to replace the older PCI, PCI-X and AGP bus standards. It is the common motherboard interface for personal computers' graphics cards, sound cards, hard disk drive host adapters, SSDs, Wi-Fi and Ethernet hardware connections. PCIe has numerous improvements over the older standards, including higher maximum system bus throughput, lower I/O pin count and smaller physical footprint, better performance scaling for bus devices, a more detailed error detection and reporting mechanism, and native hot-swap functionality. More recent revisions of the PCIe standard provide hardware support for I/O virtualization.
The Amiga 4000, or A4000, from Commodore is the successor of the Amiga 2000 and Amiga 3000 computers. There are two models: the A4000/040 released in October 1992 with a Motorola 68040 CPU, and the A4000/030 released in April 1993 with a Motorola 68EC030.
The audio/modem riser (AMR) is a riser expansion slot found on the motherboards of some Pentium III, Pentium 4, Duron, and Athlon personal computers. It was designed by Intel to interface with chipsets and provide analog functionality, such as sound cards and modems, on an expansion card.
AC'97 is an audio codec standard developed by Intel Architecture Labs and various codec manufacturers in 1997. The standard was used in motherboards, modems, and sound cards.
Mini-ITX is a 170 mm × 170 mm motherboard form factor developed by VIA Technologies in 2001. Mini-ITX motherboards have been traditionally used in small-configured computer systems. Originally, Mini-ITX was a niche standard designed for fanless cooling with a low power consumption architecture, which made them useful for home theater PC systems, where fan noise can detract from the cinema experience.
ExpressCard, initially called NEWCARD, is an interface to connect peripheral devices to a computer, usually a laptop computer. The ExpressCard technical standard specifies the design of slots built into the computer and of expansion cards to insert in the slots. The cards contain electronic circuits and sometimes connectors for external devices. The ExpressCard standard replaces the PC Card standards.
Communications and networking riser (CNR) is a slot found on certain personal computer motherboards and used for specialized networking, audio, or telephony equipment. A motherboard manufacturer may choose to provide such functionality in any combination on a CNR card. Introduced by Intel in 2000, CNR slots were once commonly found on Pentium III–class motherboards, but have since been phased out in favor of on-board or embedded components.
In computer design, microATX is a standard motherboard form factor introduced in December 1997. The maximum size of a microATX motherboard is 9.6 × 9.6 in (244 × 244 mm). However, there are examples of motherboards using microATX designation despite having a smaller size of 244 × 205 mm (9.6 × 8.1 in). The standard ATX size is 25% longer, at 12 × 9.6 in (305 × 244 mm).
The mobile daughter card, also known as an MDC or CDC, is a notebook version of the AMR slot on the motherboard of a desktop computer. It is designed to interface with special Ethernet (EDC), modem (MDC) or bluetooth (BDC) cards.
Serial Digital Video Out (SDVO) is a proprietary Intel technology introduced with their 9xx-series of motherboard chipsets.
The Apple Communication Slot, or Comm Slot, is an internal expansion data interface (slot) found in Apple Macintosh computers from the early to mid-1990s. It was designed as an inexpensive way to add communication expansion cards like network adapters or modems to Macs and Power Macs.
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.