ANSWERS: 2
  • In an 80-wire IDE (aka ATA) cable, every other wire is a ground wire. This creates an IDE bus with a more stable and consistent transmission line impedance as well as providing some shielding from crosstalk between adjacent signal lines. Basically, this means that you can run the IDE bus at a higher frequency with fewer errors. Use the 80-wire IDE cables when you can.
  • Parallel ATA interface or IDE ATA/ATAPI is the result of a long history of incremental technical development. ATA/ATAPI is an evolution of the AT Attachment Interface, which was itself evolved in several stages from Western Digital's original Integrated Drive Electronics interface. As a result, many near-synonyms for ATA/ATAPI and its previous incarnations exist, including abbreviations such as IDE which are still in common informal use. 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 centimeters) . Because of this length limit the technology normally appears as an internal computer storage interface. For many years ATA provided the most common and the least expensive interface for this application. As of 2007, it has largely been replaced by Serial ATA (SATA) in new systems. Until 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 interfacing with the rest of the computer system. The remaining connector(s) plug into drives. Parallel ATA cables transfer data 16 bits at a time. ATA's ribbon cables had 40 wires for most of its history (44 conductors for the smaller form-factor version used for 2.5" drives), but an 80-wire version appeared with the introduction of the Ultra DMA/33 (UDMA) mode. All of the additional wires in the new cable are ground wires, interleaved with the previously defined wires to reduce the effects of capacitive coupling between neighboring signal wires, 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. Though the number of wires doubled, the number of connector pins and the pinout remain the same as 40-conductor cables, and the external appearance of the connectors is identical. Internally the connectors are different; the connectors for the 80-wire cable connect a larger number of ground wires to a smaller number of ground pins, while the connectors for the 40-wire cable connect ground wires to ground pins one-for-one. 80-wire cables usually come with three differently colored connectors (blue, gray & black) as opposed to uniformly colored 40-wire cable's connectors (all black). The gray connector on 80-pin cables has pin 28 CSEL not connected; making it the slave position for drives configured cable select

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