Parallel ATA (PATA/IDE/EIDE)

In this video from ITFreeTraining I will look at Parallel ATA, also known as IDE and EIDE. This is an old technology used to connect storage devices. Nowadays obsolete, it is something you need to have a basic understanding of for the exam.

Download the PDF handout: http://itfreetraining.com/handouts/ap/1c40.pdf

Parallel ATA (PATA)
0:15 Nowadays, all the technologies that I am going to look at come under what is called Parallel ATA otherwise known as PATA. You may sometimes see it referred to as other names, so it helps to have a very basic understanding of where the names came from. Since the technology is obsolete nowadays, you don’t really need to understand what the differences are, just be able to understand what the terms mean.

To start with, the ATA part in the name stands for AT Bus Attachment. AT stands for Advanced Technology which was used with the first IBM PC back in 1984. It is essentially a standard for cables which are used to connect devices to the computer.

The first version was created by Western Digital. Western Digital called this version Integrated Device Electronics or IDE. IDE refers to any hard disk with a built-in controller. Thus, technically all hard disks are IDE drives; however, the term IDE only gets used for old hard disks that use the 40-pin cable – more on that in a moment.

The technical name later changed to PATA, but you will often see it still referred to as IDE. For example, the exam will most likely refer to the cable as an IDE cable.

The cable itself is a 40-pin ribbon cable. The ribbon cable is bulky. Due to the width of the cable, this can block air flow in the computer. Given that it works in parallel, 16 bits of data are transferred at once. The important thing to remember is not how many bits can be transferred, but rather that it transfers data in parallel rather than serial as modern connections do.

The standard supports two drives. This is why there are three connections on the cable. One end is plugged directly into the motherboard; the other two connections are plugged into the storage devices. It does not matter which connector gets plugged into the motherboard, but you will generally find that there is a larger gap between the middle connector and the end connectors on one side. Generally, you would plug this end in the motherboard to give you more cable length to attach your devices to.

The name IDE was quite popular at the time, so you will often hear the cable referred to as an IDE cable or the plugs on the motherboard referred to as IDE. Originally the standard was designed to be used with hard disks; however, the standard was later changed to include other devices.

ATA Packet Interface (ATAPI)
2:42 To add additional devices, the ATA Packet Interface protocol was added. This protocol allows different types of devices to be connected. The original Parallel ATA design was made only to be used with hard disks or devices that emulated a hard disk. Some devices have additional features that are not found in hard disks. For example, devices like CD-ROMs and tape drives have the ability to eject media whereas a hard disk does not.

The ATAPI protocol allows other types of devices to be connected and any additional features that they have to be used. The protocol is designed to be open ended so that new features can be added - where before you were limited to the features the protocol originally had.

The original Parallel ATA design was very limited in this respect. You may sometimes see a device referred to as ATAPI or ATAPI compatible. This is referring to this protocol and is still in use with newer devices like SATA devices. So, don’t get confused when you see ATAPI, it is only referring to the protocol used to transfer data and commands from the computer to the device.

Improvements
3:53 There have been a number of improvements to Parallel ATA since it was released. The technology is now quite old and obsolete, so if you purchase a motherboard there is a very good chance it will support the newest standard. Nowadays you generally just hear it referred to as IDE or PATA.

One of the first improvements was Enhanced IDE. You will not hear this term anymore as it is assumed that any Parallel ATA connection supports this standard. Later on, Ultra-ATA was introduced which was a revision of the standard that increased the speed. Once again, you probably won’t hear this term used, but may see it on a product packaging.

Description to long for YouTube. Please see the following link for the rest of the description. http://itfreetraining.com/handouts/ap/1c40

References
“The Official CompTIA A+ Core Study Guide (Exam 220-1001)” Chapter 3 position 7999-8197
“CompTIA A+ Certification exam guide. Tenth edition” Pages 296-298

Credits
Trainer: Austin Mason http://ITFreeTraining.com
Voice Talent: HP Lewis http://hplewis.com
Quality Assurance: Brett Batson http://www.pbb-proofreading.uk

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