Advanced Technology Attachment

Its the official name for the IDE port, responsible for connecting IDE devices to the PC. This port does not control the hard disk, so it's not a "controller". Control of IDE drivers is inside the drive itself.

This port has 40 pins using a 40-wire flat-cable to connect hard disks (or any other IDE device) to PC. For ATA/66 hard disks and above it is necessary a 80-wire flat-cable, which still uses a 40-pin connector. The extra wires are grounding, used to cancel EMI (electromagnetic interference).

Usually motherboards have two IDE ports embbeded on the board, but some more recent motherboards based on the new Serial ATA (SATA) standard have just one ATA port.

With the released of the Serial ATA port, the ATA port we are talking about started do be called PATA (Parallel ATA).

This standard has several transfer rates, listed below. To achieve any of these transfer rates several requirements must be met: the port must support the transfer rate, the hard disk must support the transfer rate, a special cable must be used when connecting devices from ATA/66 up and the operating system must be correctly configurated (with bus mastering drivers, i.e. IDE drivers installed and DMA mode enabled). If these requirements aren't met the hard disk will be accessed with a lower transfer rate.

Standard	Mode	Maximum Theoretical Transfer Rate
ATA	mode 0, single word	2.1 MB/s
ATA	mode 0, multi word	4.2 MB/s
ATA	mode 1, single word	4.2 MB/s
ATA	mode 2, single word	8.3 MB/s
ATA-2	mode 1, multi word	13.3 MB/s
ATA-3	mode 2, multi word	16.6 MB/s
ATA-4	UDMA mode 1	25 MB/s
ATA-4 (a.k.a ATA/33)	mode 3 or UDMA mode 2	33.3 MB/s
ATA-5	UDMA mode 3	44.4 MB/s
ATA-5 (a.k.a. ATA/66)	UDMA mode 4	66.6 MB/s
ATA-6 (a.k.a. ATA/100)	UDMA mode 5	100 MB/s
ATA-7 (a.k.a. ATA/133)	UDMA mode 6	133 MB/s

click to enlarge
Figure 1: IDE ports on a motherboard.

click to enlarge
Figure 2: "Parallel" IDE hard drive (ATA) connectors.

click to enlarge
Figure 3: "Serial" hard drive (SATA) connectors.