IDE

(1) (Integrated Development Environment) A set of programs run from a single user interface. For example, programming languages often include a text editor, compiler and debugger, which are all activated and function from a common menu.

(2) (Integrated Drive Electronics) A hardware interface widely used to connect hard disks, optical discs and tape drives to a PC. Introduced in 1986 with 20MB of storage, capacities increased a thousandfold in less than two decades. Compared to the SCSI interface, IDE has been the more economical choice.

The IDE interface is officially the AT Attachment (ATA) specification, and "IDE drives" and "ATA drives" are synonymous. The name came from the IBM PC/AT, which was the first PC to use the drives.

Built-In Electronics

The controller electronics are built into the IDE drive itself, requiring a simple circuit in the PC for connection. IDE drives were attached to earlier PCs using an IDE host adapter card. Subsequently, two Enhanced IDE (EIDE) sockets were built onto the motherboard, with each socket connecting two drives via a 40-pin ribbon cable for CD-ROMs and similar devices and an 80-wire cable for fast hard disks (see below).

Master and Slave

IDE drives are configured as master and slave. Jumper pins on the drive itself are used to set up the first drive on the cable as master and the second one, if present, as a slave.

ATAPI

The ATAPI (ATA Packet Interface) was developed to allow CD-ROM drives to run over the IDE/ATA interface by using commands similar to SCSI drives. ATAPI is essentially ATA for peripherals such as CD-ROMs, DVDs and tapes.

The ATA Numbers

As improvements were made to the IDE/ATA interface, a new version number was added. ATA-2 (Fast ATA) defined the faster transfer rates used in Enhanced IDE (EIDE). ATA-3 added interface improvements, including the ability to report potential problems (see S.M.A.R.T.). Starting with ATA-4, either the word "Ultra" or the transfer rate was added to the name in various combinations. For example, at 33 MBytes/sec, terms such as Ultra ATA and ATA-33 have been used. In addition, Ultra ATA-33, DMA-33 and Ultra DMA-33 are also found. Following are the transfer rates for the various ATA modes. See SATA and Cable Select.

                 Transfer       Transfer
 IDE              Rate           Rate     Pins
 Drive     PIO   MBytes   DMA   MBytes     in
 Type      Mode  per sec  Mode  per sec   Cable

 ATA       0      3.3     0      4.2      40
 ATA       1      5.2                     40
 ATA       2      8.3

 ATA-2, 3  3     11.1     1     13.3      40
 ATA-2, 3  4     16.6     2     16.6      40

 ATA-4 (ATA-33)           2     33.3      40

 ATA-5                    0     16.6      40
 ATA-5                    1     25.0      40
 ATA-5 (ATA-33)           2     33.3      40
 ATA-5                    3     44.4      80
 ATA-5 (ATA-66)           4     66.6      80

 ATA-6 (ATA-100)          5    100.0      80

 ATA-7 (ATA-133)          5    133.0      80

 Serial ATA (SATA)        5    150.0       4
 Serial ATA II (SATA II)  5    300.0       4

Internal IDE Cables

Starting with ATA-66 drives, 80-wire cables (with 40 more ground wires) replaced the 40-wire ribbon cable. They plug into the same 40-pin socket with one pin removed.

Fault Tolerance for IDE Drives

Arco Computer Products was the first to provide RAID 1 (mirroring) using IDE drives rather than SCSI. The IDE cable from the motherboard plugs into the DupliDisk PCI card or "no-slot" version (above) from which two cables go out to primary and secondary drives. (Image courtesy of Arco Computer Products, Inc., www.arcoide.com)

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Ide	ide cable
Ide Interface	ide controller