IDE, SATA, PATA - Which Type of Hard Disk Should I Buy?

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Hard Disk Drive Interfaces De-mystified

There are several types of interfaces available, Which one do you choose? What do these different letters mean? How do I know which one is correct for my PC?

Technology is advancing at breathtaking pace. As soon as a new technology emerges it is named by three or four letters and expect the consumer to understand everything behind the technology and adopt it without any questions. Interface is the connector technology and more accurately it the technology of transferring data to and from the disk drives. A brief history/guide to the various technologies are described below:

IDE - Integrated Drive Electronics

This is a popular term, it really should be called ATA - Advanced Technology Attachment. One of the earliest types. Also known as ATA-1. Data transfer rate of about 8Mbps (8 million bits per second).

EIDE - Enhanced IDE

Also known as ATA-2 or fast ATA, offered speeds of upto 16Mbps.


This was a minor revision to ATA-2.


Also known as Ultra ATA/33, Ultra DMA, ATA-33 and DMA-33. Transfer speeds of upto 33Mbps. This was revised to offer support for CD ROM drives and was known as ATAPI (ATA Packet Interface).


Also known as Ultra ATA/66, ATA-66 and Ultra DMA-66. Transfer speeds of upto 66Mbps.


Also known as Ultra ATA/100, ATA-100 and Ultra DMA-100. Transfer speeds of upto 100Mbps.


Also known as Ultra ATA-133, ATA-133 and Ultra DMA-133. Offers speeds of upto 133Mbps and is expected to be the last update to the ATA standard.

SATA - Serial ATA

This is one of the latest and popular developments. The high speed serialized AT attachment. Currently SATA offers ransfer speeds of upto 150Mbps. However, this technology can offer upto 600Mbps with further development. The next stage is increasing the speed to 300Mbps.

PATA - Parallel ATA

Another new technology? NO. Since the introduction of Serial ATA, the ATA technology is now referred to as the Parallel ATA or PATA.

Some of the earlier ATA developments like IDE and EIDE are obsolete, but even today some drives are categorized as IDE or EIDE. They are bound to be of the newer ATA types, but due to the popularity of IDE and EIDE the name has stuck. Since Serial ATA gaining prominence, changing IDE to ATA would only add to the confusion.

Searial ATA II or SATA II does not exist. It is a common misconception and anyone labelling their drive as SATA II with 300Mbps(3.0Gbps) would be incorrect. The higher speed may be available in the near future, but not so at the time of writing this guide.

So, How Do I Choose a Hard Disk drive?

Firstly, you need to find out the type of disk drive your PC mainboeard can accept. Most of the latest ones can accept both ATA and Serial ATA. If this is the case then choose a Serial ATA disk drive. However, if you are on a very tight budget then you may be able to save a little by choosing an ATA/IDE disk drive.

If your computer is quite old and you need a hard disk, then there is no need to panic. ATA/IDE disk drives are backward compatible. They will work without any problems, but maybe at a reduced performance level. Always refer to your mainboard manual and the operating system before purchasing your drive. Some older operating systems cannot work with disk drives greater than 40GB.

Choosing the size or capacity of the disk drive is dependent upon the size of your wallet. It also depends on what sort of work you will be doing on your PC. If it is for holding your music collection, videos and photos then stick with a 300Gb hard disk. If it is for general work then anywhere from 80 - 160Gb will be fine. Always check the prices. Sometimes, for an additional £10 - £11 you may be able to get an additional 50Gb of space.

I have not emphasized, SCSI - Small Computer System Interface, which is another type interface. These disk drives are more commonly used on servers and workstations. due to the relative cost involved they never became popular for PCs. Unless your PC is equipped to accept SCSI, it is not easy to install SCSI disk drives. You will need to get an additional adapter/card to connect SCSI disk drives. The prices may still be relatively high as well.

If you are unsure on how to install a hard disk drive or afraid to open up the PC then External Hard disk drive would be the answer. Check Part 1 and Part 2 of my guides on external hard disk drives.

See all the guides I have written by clicking here.

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