What is ATA?

ATA (AT Attachment) is an industry standard for connecting storage to computers.

ATA replaced earlier technologies such as MFM, RLL, and ESDI. ATA currently competes with SCSI.

ATA is a specification for attaching hard drives to the AT bus. The AT specification has been extended to include other storage, such as CD/DVD drives, tape drives, and Zip drives with the Advanced Technology Attachment Packet Interface (ATAPI) additions to the specification.

ATA is also known as IDE (Integrated Drive Electronics).

Parallel ATA Cables

Parallel ATA cables originally contained 40 wires.

Parallel ATA cables with 80 wires became standard with the introduction of ATA-5.

In both types of ATA cables, only 40 wires are used to carry signals. The extra 40 wires in 80-wire cables exist to provide a ground wire for each signal wire.

These grounding wires enable the ATA subsystem to operate at higher speeds with greater reliability.

ATA Masters and Slaves

Each ATA bus supports two storage devices. The first storage device is referred to as the Master and the second storage device is called the Slave.

There are two methods for configuring which device is the master and which is the slave: drive jumpers and cable select.

Drive Jumpers

The original method for configuring Master and Slave relationships on ATA drives was to place or remove jumpers on each storage device.

The jumper definitions differ among drive manufacturers and models. The jumper setting are often printed on the drive. If not, read the drive manual or visit the drive manufacturers web page.

In a single drive configuration, some drives should be set to "Single Drive", while other drives should be set to "Master".

In a dual drive configuration, the first drive should be set to Master and the second drive should be set to Slave.

Cable Select

A newer standard for configuring Master/Slave relationships on ATA drives is to utilize the placement of the drives on the drive cable to determine the ordering.

For Cable Select to work, both of the drives and the ATA cable must support Cable Select.

To use Cable Select, the jumpers on both drives should be set to Cable Select.

Parallel vs. Serial ATA

Until version 7 of the ATA standard was released in 2004, all versions of ATA utilized parallel transfer of data from the motherboard to the drive controller built onto the disk.

The ATA-7 specification introduced Serial ATA.

The most obvious change with Serial ATA is the difference in drive cables. Other differences include:

Higher thoughput
Longer data cables
Revised power connector
Support for external drives (eSata)

Sunday, July 06, 2008

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