What is ATA (Advanced Technology Attachment)? (Explained)

What is ATA (Advanced Technology Attachment)?

ATA, or Advanced Technology Attachment refers to the standard physical interface approved by the ANSI to connect different drives, such as hard drives, CD-ROM drives, and other storage devices, to the computer system.


  • The ATA interface standard was developed and approved by The ANSI especially to allow connecting integrated, supported, or portable storage devices without needing an external controller for them to function.
  • Typically, ATA allows the devices to be connected internally to the motherboard through the interface and perform the fundamental input and output operations.
  • There is also another name by which an ATA is known, such as Integrated Device Electronics (IDE). The first ATA interface is however called Parallel Advanced technology Attachment or PATA more commonly now.
  • These interfaces are available in different standards and each of them comes with new and improved features to support different modes and speeds of data transfer.
  • You will find an ATA interface in almost every home computer designed by different manufacturers, including Apple computers, which typically use a SATA interface.

Understanding Advanced Technology Attachment (ATA)

What is ATA

Advanced Technology Attachment refers to the hardware interface standard developed by Western Digital and Compaq in the late 1980s. It is used to connect storage devices to a computer.

The ATA standard was adopted by the International Committee for Information Technology Standards or INCITS later on, and was approved by the ANSI as a standard for the computer industry.

Though AT Attachment was initially designed to be used to connect storage devices to the computer motherboard directly without the requirement of a controller, it was primarily used later on as a form of ATA hard drives.

This particular technology typically uses a parallel interface. This means that it allows transferring data at the same time over several wires.

The primary intention of it was to replace the Integrated Drive Electronics (IDE) standard, which was older and slower.

What is ATA (Advanced Technology Attachment)

ATA Devices

As for the ATA devices, there can be two different types of it mainly, such as:

  • The master device
  • The slave device

Here, the master device is actually the primary storage. This device is typically connected to the first AT Attachment interface on the motherboard.

On the other hand, the slave device is typically the secondary storage device. This is attached to the second ATA interface on the motherboard.

The connections to the motherboard are typically made through a 40-pin ribbon cable. This cable normally has two connectors.

One of these connectors is dedicated to the master device, and the other one is dedicated to the slave device.

These separate connectors are usually marked with “M” and “S” respectively, to indicate which device each is for.

The ATA devices can be used for two specific purposes, such as:

  • They can be used to store data, including documents, pictures and others.
  • They can be used to run programs as well, such as applications and operating systems.
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Though replaced by newer and faster interface standards, such as SATA, the ATA devices are still used in quite a few older computer systems.

Apart from that, they are also used in a few newer systems as well, usually as a secondary storage alternative.


Usually, the ATA interface is a set of thin wires combined into a cable bus. These wires are actually utilized to transmit data in and out of the disk drives through them.

In the beginning, the ATA interface supported parallel communication and was therefore referred to as Parallel ATA (PATA).

It then used a 40-pin controller cable and supported transferring data through it at a speed ranging between 16 bits and 32 bits at a time.

However, over time, PATA was substituted by Serial ATA (SATA) in the computer systems launched from 2007 onwards, such as in the Apple computers.

This offered even faster data I/O speeds. Typically, you will find an ATA interface in almost every home computer today.

The ATA connectors mainly have two parts such as:

  • The data portion, which is used to transmit data typically through 26 pins and
  • The power portion, which supplies power to the devices usually through 14 pins.


The specific features of the Advanced Technology Attachment include the following:

  • Compatibility – It is compatible with and supported by a wide range of desktop and laptop computers as well as other systems.
  • Transfer speed – The ATA devices can support a data transfer speed of up to 133 megabytes per second, with the newer standards supporting even a much higher speed than that.
  • Cable length – The ATA cables are pretty long, typically measuring up to 18 inches (46 cm) in length, which is quite long to allow for flexibility in placing the storage device within the computer.
  • Device support – The ATA interface can support up to two devices in each interface and per cable, which allows connecting several different storage devices to a single motherboard.
  • Hot swapping – The interface allows hot swapping, or removing or adding a device without needing to shut down the computer system.
  • Cable connectors – The cables used in ATA usually come with a 40-pin connector on the motherboard side. The connector on the device side may be equal to or larger, depending on the particular device it is designed to connect to, with the number of pins ranging between 40 and 44.

The most unique aspect of the ATA interface is with respect to the data transfer modes. There are specifically two different data transfer modes supported by ATA, such as:

The PIO mode relies on the Central Processing Unit or CPU of the computer for it to function, while the DMA mode allows the devices to transfer data to and from the memory of the computer directly.

This eventually helps in improving the overall performance of the system.

ATA Layout

Typically, the ATA interfaces support a 40-pin connector to support up to two 3.5-inch disk drives in each interface.

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Here is the list of functions performed by each of the pins of a traditional 40-pin ATA interface:

  • Pin 1 – Reset
  • Pin 2 – Ground
  • Pin 3 – Data 7
  • Pin 4 – Data 8
  • Pin 5 – Data 6
  • Pin 6 – Data 9
  • Pin 7 – Data 5
  • Pin 8 – Data 10
  • Pin 9 – Data 4
  • Pin 10 – Data 11
  • Pin 11 – Data 3
  • Pin 12 – Data 12
  • Pin 13 – Data 2
  • Pin 14 – Data 13
  • Pin 15 – Data 1
  • Pin 16 – Data 14
  • Pin 17 – Data 0
  • Pin 18 – Data 15
  • Pin 19 – Ground
  • Pin 20 – Key
  • Pin 21 – DDRQ
  • Pin 22 – Ground
  • Pin 23 – I/O Write
  • Pin 24 – Ground
  • Pin 25 – I/O Read
  • Pin 26 – Ground
  • Pin 27 – IOC HRDY
  • Pin 28 – Cable Select
  • Pin 29 – DDACK
  • Pin 30 – Ground
  • Pin 31 – IRQ
  • Pin 32 – No Connect
  • Pin 33 – Addr 1
  • Pin 34 – GPIO_DMA66_Detect
  • Pin 35 – Addr 0
  • Pin 36 – Addr 2
  • Pin 37 – Chip Select 1P
  • Pin 38 – Chip Select 3P
  • Pin 39 – Activity
  • Pin 40 – Ground

ATA Standards

The Advanced Technology Attachment (ATA) interface comes in different standards or versions, such as Fast ATA, ATA-1, ATA-2, ATA-3, ATA-4, ATAPI-4, ATA-5, ATA-6, and Ultra ATA.

Over the years, there have been different standards for ATA introduced with multiple revisions and updates, and each of these standards comes with new features that have improved their performance.

Here are some of the major standards of the ATA, with a brief description of the capability and history of each.


This is the original ATA standard. It was developed by Control Data Corporation, Western Digital, and Compaq and was released in 1994.

This specific ATA standard supports data transfer rates of up to 8.3 MB/s through an 8-bit or 16-bit interface. Apart from that, this standard also offered support for PIO modes 0, 1, and 2.


This revised standard of ATA-1 is also known as Enhanced Integrated Device Electronics or EIDE, and sometimes as Fast ATA or Fast IDE. It was released in 1996 and was approved by the American National Standards Institute or ANSI under document number X3.279-1996. It supports data transfer rates of up to 16.6 MB/s.

The other notable enhancements of this ATA standard are:

  • It introduced two new PIO modes, 3 and 4.
  • It also introduced DMA modes 1 and 2.
  • It offered Logical Block Addressing or LBA support.
  • It offered support for drives up to 8.4 GB.


This is the improved version of ATA-2 and is also referred to as Ultra DMA (UDMA). This standard was released in 1997 and was also approved by the ANSI under document number X3.298-1997.

In addition to allowing a data transfer rate of up to 33.3 MB/s, the ATA-3 standard also offered additional security features as well as the S.M.A.R.T feature.


This enhanced version of ATA-3 is also referred to as Ultra DMA/33 or Ultra ATA/33. This specific ATA standard was released in 1998 and was approved by the ANSI on August 19, 1998, under document NCITS 317-1998. It supports a data transfer rate of up to 33.3 MB/s and includes ATAPI packet commands.

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This revised standard of the ATA-5 standard is also known as Ultra DMA/66, which can support a data transfer speed of up to 66 MB/s.

This standard was approved by the ANSI on December 13, 2000, under document NCITS 340-2000. The unique aspect of this particular ATA standard is that it has the ability to detect between 40- and 80-wire cables.


This particular ATA standard is also known as Ultra DMA/100. It was released in 2002 and approved by the ANSI on May 16, 2001, under document NCITS 347-2001. The standard supports a data transfer rate of up to 100 MB/s.


This ATA standard is also referred to as Serial ATA or SATA and was released in 2003. It can transfer data at a high rate of up to 1.5 GB/s.


This ATA standard was released in 2004 and is also called SATA II. The data transfer rate supported by this standard is even higher, reaching up to 3 GB/s.


This ATA standard is also called SATA III or SATA 6G. It was released in 2011 and data can be transferred through this interface at a high speed of up to 6 GB/s.

Why is Advanced Technology Attachment Important?

Advanced Technology Attachment is important because it allows transferring data between the storage device and the motherboard at a much faster speed.

The fact that it uses a thin cable allows hot swapping devices, which means you can plug in or unplug a device while it is still operating.

Another important aspect of the ATA standard is that it is backwards compatible. This means that you can use the new ATA drives, apart from the SATA, with ATA interfaces of older versions.

In addition to that, you will also be able to take advantage of the additional new features introduced in all of its future releases.

For example, if you wish to use the ATA-4 standard, it will also offer support for PIO modes 0, 1, 2, 3, and 4 of data transmission, despite the fact that these particular modes were first introduced in the ATA-1 and ATA-2 standards.


The Advanced Technology Attachment (ATA) standard is a significant development with respect to computer interfaces that has improved data transfer rates quite notably.

Available in different standards, features and capabilities, these different ATA standards surely add to the computing pleasure of the users.

About Dominic Cooper

Dominic CooperDominic Cooper, a TTU graduate is a computer hardware expert. His only passion is to find out the nitty gritty of all computers since childhood. He has over 12 years of experience in writing, computer testing, and research. He is not very fond of social media. Follow Him at Linkedin