Storage Interfaces

IDE Configuration

The IDE/ATA interface is the most common storage interface, making it readily available and very cost effective. IDE/ATA devices are generally very easy to configure and install as well. Compared to other interfaces, there are some limitations inherent with IDE/ATA.

Controller and Device Configuration

Most systems have two IDE/ATA channels, a primary and a secondary. Each channel can have a maximum of two connected devices. These channels communicate with the computer system through interrupt requests (IRQs). Standard computer systems dedicate IRQ 14 to the primary channel, and IRQ 15 to the secondary IDE channel.

Device Configuration

IDE/ATA devices that share a channel distinguish themselves from one another by using the master and slave designations. This designation is assigned using jumpers, small metallic bridges that close an electrical circuit. Despite the nomenclature, the master device doesn't have any special relation to the slave device; rather, this designation is simply a way for the controller to differentiate between the signals of the two devices. The device designated as master will have its hard drive letter assigned to it first.

Each channel has its own master and slave device. Generally, if only one device is to be used on a channel, it should be configured as the master device. Slower devices such as CD-ROM drives and tape drives should be isolated on the secondary controller for optimal performance.

IDE/ATA Limitations

As stated above, each IDE/ATA channel is limited to two devices. Because systems typically have two channels, this means the system can have a maximum of four IDE devices. External devices cannot be connected to these channels. The communication path is only 16 bits wide, limiting the data transfer rate.

Advantages

Limitations

Very cost effective
Wide variety of products available
Simple configuration process

Only two devices per channel
Uses slower 16-bit bus
Internal devices only