Stands for "Enhanced Integrated Drive Electronics." EIDE is an improved version of the IDE drive interface that provides faster data transfer rates than the original standard. While the original IDE drive controllers supported transfer rates of 8.3 Mbps, EIDE can transfer data up to 16.6 Mbps, which is twice as fast.
The term EIDE can be a bit ambiguous, since it technically refers to an ATA standard known as ATA-2 or Fast ATA. Therefore, the terms EIDE, ATA-2, and Fast ATA may be used synonymously. To add to the confusion, EIDE may also refer to the ATA-3 standard, which is similar to ATA-2, but includes additional features. ATA-3 supports the same maximum data transfer rate as ATA-2, but has SMART support and uses a 44 pin connector.
While EIDE was the most common drive controller used for many years, it has since been replaced by updated versions of the ATA standard that support Ultra DMA. These include the ATA-4 through ATA-7 standards, which provide data throughput rates from 33 to 133 Mbps. Most modern computers use a completely new standard called "Serial ATA," or SATA, which supports even faster transfer rates.