IDE Devices

  IDE stands for Integrated Device Electronics. An IDE interface is a way of connecting a device, typically storage, to a computer system. The IDE interface was originally used to integrate hard disk drives to a computer system. Over time a number of other devices have come to use the IDE interface including CD-Rom drives, tape drives, zip drives, etc.

  The IDE interface was developed as a way of increasing the performance and cost of mass storage on computer systems, namely the hard disk. When hard disks were originally added to computer systems there were two discrete componants that were required to accomplish the addition. First was the disk drive and the second was disk controller electronics, or controller card.

  As performance increased in computer systems the mechanical disk drive often became the target of performance improvement. It was a well known problem of the separation of the hard disk drive and the controller electronics. The two componants were generally made by two different manufacturers with different standards and concepts as to how everything should be implemented. To make matters worse it was very important that each manufacturers products were compatible with everyone elses product. The only way to achieve total compatibility was by hindering performance.

  The disk drive manufacturers knew that if they were to "integrate" the controller into their hard disk they would be able to tune the performance of each with the other. This tuning would enable maximizing performance of hard disk storage technology and changing hard disk technology forever.

  An IDE channel, of which there can be up to four, can support three distinct configurations of devices connected to that channel. The configuration is performed on the IDE device itself, typically with jumpers. The IDE channel is identified by the connection of a single cable to an IDE port on a computer system. If there is more than one cable, then there is more than one IDE port on the computer.

  The first configuration is that of a single device. This configuration is where there is only one single IDE device connected to the IDE cable and port. When configured in this manner the IDE device must be set distinctly as a single IDE device.

  The second configuration is that of a master device. This configuration is where there are two IDE devices connected to the same IDE cable and port. When using this configuration only one of the devices that are connected to the same cable and port may assume the role of the master device! When configured in this manner the IDE device must be distinctly set as a master IDE device.

  The third configuration is that of a slave device. This configuration is where there are two IDE devices connected to the same IDE cable and port. When using this configuration one of the devices is configured as the master device and the other is configured as the slave device. When configured in this manner the IDE device must be distinctly set as the slave device.

  As far as I am aware there is only one manufacturer who strictly adheres to the three distinct states and has a jumper setting for each state. That manufacturer is Western Digital, every other device manufacturer combines the master and single configuration into one single setting. For this reason is is very important when adding a second IDE device to the same cable to determine if the first device has the "single" configuration. If so then you must change that device from the simgle configuration to the master configuration.

  The single, master, and slave rules only apply when connecting devices onto the same cable. If they are connected to different cables (different IDE ports) it is as though they were by themself.


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Modified 04/14/2005