Advanced Technology AttachmentEssay Preview: Advanced Technology AttachmentReport this essayAT AttachmentAdvanced Technology Attachment (ATA) is a standard interface for connecting storage devices such as hard disks and CD-ROM drives inside personal computers. The standard is maintained by X3/INCITS committee T13. Many synonyms and near-synonyms for ATA exist, including abbreviations such as IDE and ATAPI. Also, with the market introduction of Serial ATA in 2003, the original ATA was retroactively renamed Parallel ATA (PATA).
Parallel ATA standards allow cable lengths up to only 18 inches (46 centimetres) although cables up to 36 inches (91 cm) can be readily purchased. Because of this length limit, the technology normally appears as an internal computer storage interface. It provides the most common and the least expensive interface for this application.
HistoryThe name of the standard was originally conceived as PC/AT Attachment as its primary feature was a direct connection to the 16-bit ISA bus then known as AT bus; the name was shortened to an inconclusive “AT Attachment” to avoid possible trademark issues.
An early version of the specification, conceived by Western Digital in late 1980s, was commonly known as Integrated Drive Electronics (IDE) due to the drive controller being contained on the drive itself as opposed to the then-common configuration of a separate controller connected to the computers motherboard — thus making the interface on the motherboard a host adapter, though many people continue, by habit, to call it a controller.
Enhanced IDE (EIDE) — an extension to the original ATA standard again developed by Western Digital — allowed the support of drives having a storage capacity larger than 528 megabytes (504 mebibytes), up to 8.4 gigabytes. Although these new names originated in branding convention and not as an official standard, the terms IDE and EIDE often appear as if interchangeable with ATA. This may be attributed to the two technologies being introduced with the same consumable devices — these “new” ATA hard drives.
The interface at first worked only with hard disks, but eventually an extended standard came to work with a variety of other devices — generally those using removable media. Principally, these devices include CD-ROM and DVD-ROM drives, tape drives, and large-capacity floppy drives such as the Zip drive and SuperDisk drive. The extension bears the name AT Attachment Packet Interface (ATAPI), which started as non-ANSI SFF-8020 standard developed by Western Digital and Oak Technologies, but then included in the full standard now known as ATA/ATAPI starting with version 4. Removable media devices other than CD and DVD drives are classified as ARMD (ATAPI Removable Media Device) and can appear as either a floppy or a hard drive to the operating system.
The move from programmed input/output (PIO) to direct memory access (DMA) provided another important transition in the history of ATA. As every computer word must be read by the CPU individually, PIO tends to be slow and use a lot of CPU resources. This is especially a problem on faster CPUs where accessing an address outside of the cacheable main memory (whether in the I/O map or the memory map) is a relatively expensive process. This meant that systems based around ATA devices generally performed disk-related activities much more slowly than computers using SCSI or other interfaces. However, DMA (and later Ultra DMA, or UDMA) greatly reduced the amount of processing time the CPU had to use in order to read and write the disks. This is possible because DMA and UDMA allow the disk controller to write data to memory directly, thus bypassing the CPU.
ATA-6 introduced 48 bit addressing, increasing the limit to 128 PiB (or 144 petabytes). Some OS environments, including Windows 2000 until Service Pack 3, did not enable 48-bit LBA by default, so the user was required to take extra steps to get full capacity on a 160 GB drive.
Parallel ATA Interface cable and SocketUntil the introduction of Serial ATA, 40-pin connectors generally attached drives to a ribbon cable. Each cable has two or three connectors, one of which plugs into an adapter that interfaces with the rest of the computer system. The remaining one or two connectors plug into drives. Parallel ATA cables transfer data 16 bits at a time.
ATAs ribbon cables had 40 wires for most of its history, but an 80-wire version appeared with the introduction of the Ultra DMA/66 (UDMA4) mode. All of the additional wires in the new cable are ground wires, interleaved with the previously defined wires. The interleaved ground wire reduces the effects of capacitive coupling between neighboring signal wires, thereby reducing crosstalk. Capacitive coupling is more of a problem at higher transfer rates, and this change was necessary to enable the 66 megabytes per second (MB/s) transfer rate of UDMA4 to work reliably. The faster UDMA5 and UDMA6 modes also require 80-conductor cables.
80-wire cables usually come with three differently colored connectors (blue, gray & black) as opposed to uniformly colored 40-wire cables connectors (all black).
Multiple devices on a cableIf two devices attach to a single cable, one is commonly referred to as a master and the other as a slave. The master drive generally appears first when the computers BIOS and/or operating system enumerates available drives. If there is a single device on a cable, in most cases it should be configured as master. However, some hard drives have a special setting called single for this configuration.
Serial ATASATA is expected to eventually replace the older technology ( Parallel ATA or PATA). Serial ATA adapters and devices communicate over a high-speed serial link. There exists a point to point link between the host and the device and no sharing of cable is used.
ArchitectureAt the physical layer of the Serial ATA architecture, the data-connection is formed by two pairs of (unidirectional) signal wires. Over these wires, SATA uses Low Voltage Differential Signaling (LVDS), enabling much higher (per-wire) signalling rates (1.5 Gbit/s and up) than traditional parallel ATA. Byte data is encoded and transmitted using 8B/10B encoding, which is also used in Ethernet, Fibre Channel, PCI Express, etc. The switch from a parallel to serial electrical scheme facilitates future upgrades to performance, and lowers costs (compared to a comparably fast parallel-interface.). Vendor implementations may include additional functionality (such as simulated RAID) above and beyond the SATA specification, but require device-specific
s. The SATA design can provide better signal quality (and/or power quality) than a traditional non-compatible (ATA) PCIe design, where high power handling and throughput is a challenge. In the SATA specifications, high power handling is preferred for low cost and low power and latency, while power and latency can be enhanced with SATA devices. As a result, multiple SATA devices can coexist freely. There remain some drawbacks over a full PCI 3.0-only mode: the large number of devices required for this, and its relatively small bandwidth, cost, and performance (see Device Choice).
While PCIe 3.0 was a popular choice, most users of its form factors continue to favor older form-factor designs.
The Intel® HD Graphics 4000 has an integrated Intel® HD Graphics 4000 technology, which makes the device easier to use (compare with older Intel® HD Graphics 4000s) and reduce the size of components. In particular, the new design gives the device more than one PCIe controller to support. Since the HD Graphics is designed for a fast-sync mode, PCIe technology in this form factor allows for better flexibility for connecting multiple devices, such as an SSD, or a network-level interface. All PCIe devices in this form factor may interoperate, and may offer superior connectivity to those devices with similar features. A key advantage of PCIe 3.0-only is increased performance through a greater ability to use more peripherals, such as USB ports. In addition, a PCIe 3.0-only solution can provide greater redundancy and flexibility to different components in an integrated device (instead of by requiring USB 3.0-only drivers and PCIe drivers).
The Intel® High Bandwidth Bandwidth (HBM) Technology provides better wireless performance than the PCI-Express (PCIe) connectors. In fact, it provides slightly less bandwidth, but still has better throughput with higher-bandwidth interface connectors. Moreover, HBM is much more efficient than PCI-Express, allowing it to provide less capacity than PCI-Express. Additionally, since PCI-Express uses more bandwidth, it provides better performance by using less power to the processor. In the same way that a USB 3.0-only bus can be used simultaneously to access up to 4x the available performance from its PCI-Express connectors, to more effectively optimize performance for the single or multiple devices in use.
The Intel® Ethernet Protocol (EPR) provides an alternative high-bandwidth standard for connecting peripherals and protocols that are easily accessible to consumers worldwide. This standard supports all PCIe devices, providing an easy-to-use path to data transfer, communication, and management.
The PCIe 3.0 solution and the PCIe 3.1-to-2 solution are based upon the PCIe protocol, that is, the latest version of PCIe 3.x standard for all devices running software, hardware, and services such as BIOS, operating systems, and operating system components