What Is an EIDE Hard Drive?

Enhanced Integrated Drive Electronics (EIDE) hard drives are actually another name for a standard of drive communication known as ATA (Advanced Technology Attachment) or PATA (Parallel ATA). ATA is different from other drive standards in that the controller for the drive resides on the drive, meaning the drive can directly connect to the controller on the motherboard. ATA is the most common drive technology used in PCs today.

Types

EIDE drives fall under the ATA-2 standard. Also known as Fast ATA, Fast IDE or Ultra ATA, it is an improvement on the original ATA/IDE standard. It supported drive sizes up to 8.4GB and introduced new PIO (Programmed Input/Output) modes which sped up data transfers between the drive and the computer. ATA-2 is considered obsolete today, but drives that fall under newer ATA standards are still considered EIDE, even thoguh technically they are not. The current ATA standard is SATA, or Serial ATA which uses a different transmission standard than older PATA that significantly increases speed.

History

The original IDE/ATA standard was developed by Western Digital and Compaq. It was approved as a standard by ANSI (American National Standards Institute), a group that creates and approves standards in the computer industry, on May 12, 1994. It was replaced by ATA-2/EIDE in 1996. ANSI approved ATA-3 in 1997, ATA-4 in 1998, ATA-5 in 2000 and ATA-6 in 2001---the same year SATA was approved.

Function

EIDE is a PATA technology, meaning data is transmitted in parallel (or side by side) across 16 of the wires in the cable. EIDE drives use a ribbon cable that contains 40 connectors, but 80 conductors (wires). Each of the 40 connectors connects to a conductor with one conductor that dead ends lying in between. Data transfer is actually the movement of electricity. And just like electricity can jump across gaps, it could jump to an adjacent conductor, destroying the data on both. The dead end conductors catch any stray data and protect the data on the adjacent wires. This is a significant improvement over ATA/IDE as that standard used only the 40 wires to carry data.

Features

EIDE drives, under the ATA-2 standard, supported transfer rates up to 16.6 MBps (MegaBytes per second). This means it could transfer roughly four mp3 songs in one second. It also supported DMA (Direct Memory Access) modes 1 and 2. DMA allows the hard drive to place data directly into system memory, bypassing many controllers and improving overall performance. It was also the first standard to support Large Block Addressing (LBA). LBA is what first allowed drives to be larger than 528 MB.

Misconceptions

The term EIDE is commonly used to describe any drive that uses an 80 conductor cable. However, EIDE was only officially used to describe ATA-2 and 3. Starting with ATA-4, the standards were referred to as ultra-ATA and introduced the ATAPI (ATA Packet Interface) standard which allowed CD-ROMs, tape drives and other devices.

References

• Computer Hope, free computer help for everyone.