What is an IDE Hard Drive?

The IDE hard drive is a broad term for PC hard drives. The acronym IDE stands for Integrated Drive Electronics. The IDE standard is an effort to make hard drives more compatible between vendors by “integrating” drive specific electronics directly on the drive itself rather than onto the bus controller card.

In 1994, Western Digital, created the "Enhanced" IDE standard, now known as EIDE. This standard is backwards compatable with IDE, which means that an EIDE hard drive can use an IDE cable and controller. The reverse is also true, you can connect an IDE drive to an EIDE controller and cable. Besides, this really only matters if you have older hardware. If all of your controllers, cables, and drives were built after about 1996, then it will support the EIDE standard.

Because the term IDE was too general, the drive and interface became known as the IDE/ATA standard. ATA stands for Advanced Technology Attachment. It represents the interface standard for the PC that goes back to the 1980s. This standard has been upgraded through the years with performance improvements.

The IDE/ATA cable is a 2 inch wide ribbon cable with a maximum length of 18 inches. This short length limits the use to internal hard drives. Each ribbon cable can attach to two hard drives. If two drives are attached to a cable then the drive jumpers must be set to enable one as the master (drive 0) and the other as the slave (drive1). The ribbon cable is also known as a parallel cable because it can transfer 16 bits of data at a time.

The most recent improvement has been the development of Serial ATA (SATA). To avoid confusion with this new standard, the term IDE/ATA has been changed to IDE/PATA. This allows drive manufacturers to differentiate between the older parallel interface and the newer serial interface of the SATA Hard Drive.

It seems counter-intuitive to think that a serial cable could transfer data faster than a parallel cable since a serial cable can only transfer 1 bit at a time. The issue with the parallel cable is that higher clock rates cause the data lines to interfere with each other. There is therefore a hard upper limit on the speed of the parallel cable. Thus, at a high enough speed, a serial cable will transfer data faster than a parallel cable.

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