IDE and EIDE interfaces

The EIDE interface controls the hard drive on most Windows computers. Often it controls the CD-ROM drive or DVD drive as well. All modern Windows computers have a built-in EIDE controller or two, sitting on the motherboard, usually attached with wide ribbon cables to all the hard drives and CD drives in the PC.

The IDE interface is an ancestor of EIDE, and you still find hard drives that are designed to run with IDE. If your computer has an EIDE interface, you can probably plug an IDE hard drive into it, but you're talking slug city.

IDE and EIDE interfaces are rarely used for external devices because the length of the cable connecting the controller to the device is quite limited.

Serial ATA interface

If you've ever poked around the innards of your computer, no doubt you've noticed those long, not-so-flexible "ribbon cables" that connect hard drives, CD drives, floppies, and the like to the motherboard. A a number of companies had introduced new technology that would make ribbon cables obsolete.

The Serial ATA approach replaces those 40- or 80-wire ribbons with a single cable that looks like a stereo patch cord. Of course, Serial ATA is faster, smarter, better than its predecessor. Of course, it's completely incompatible - you need Serial ATA hard drives, CD drives, and the like to go on one end of the cable; and your PC has to have Serial ATA sockets on its motherboard. At this point, it's anyone's guess whether Serial ATA will roll over the market or turn into another dodo.

SCSI interface

The SCSI interface is for fast devices such as highperformance disk drives and tape drives. It is used for both internal and external devices, although USB and FireWire (see the following two sections) have largely taken over external connections.

Very few Windows computers have a SCSI controller built in. A controller must be installed in one of the slots on the computer's motherboard. Here's the reason why: Although SCSI is theoretically faster than EIDE, in practice very few people recognize much of a speed improvement when moving "up" from EIDE to SCSI. But SCSI is almost always (and sometimes quite considerably) more expensive than EIDE. Unless you have a crying need for SCSI speed, stick with EIDE.