Hardware components of the PC
Storage device interfaces
Enhanced Integrated Drive Electronics (EIDE)

Enhanced Integrated Drive Electronics (EIDE) is the most common interface standard for connecting storage devices such as hard drives, CD-ROM, DVD-ROM, and removable drives to a PC workstation. An EIDE controller is integrated onto the device and the interface is a connector on the motherboard or expansion card.

The majority of motherboards have dual integrated or on-board EIDE interfaces as standard, defined as primary and secondary channels, with both channels capable of accommodating two devices, a master and slave.

EIDE is a single threaded architecture. This means that if two devices are connected to a single channel, one will be idle while the other is executing a command. Both devices cannot communicate with the interface at the same time. Installing storage devices to effectively utilise this limitation would require the fastest devices to be the masters and slower devices the slaves spread across both channels.

Advantages of EIDE:

• Price/ performance is very good
• Devices are inexpensive due to high volumes of production and simplified testing requirements
• Devices are supported directly by system BIOS.

Limitations of EIDE:

• The amount of devices is limited, with a maximum of two devices per channel, and usually only two channels per system
• Single threaded operation that allows only one device to communicate with a single interface at a time
• The distance limitation of this specification allows only internal devices, so inside the box devices only.