Since the market has come to be dominated by the two interface standards, IDE/ATA and SCSI, the question of "which is better" has been bandied about endlessly on the Internet and in other places as well. The simple answer is that neither is better than the other, absolutely. Why? Because if one were clearly superior to the other in every way, the superior one would have taken over the market completely and forced the other one out. The fact that both are in common use (and have been for many years) proves that both have valid reasons for being on the market. Contrast this to the older ST-506/412 interface, for example, which was made obsolete by IDE/ATA since it had no advantages to cause it to persist, and disappeared very quickly.

Whether IDE/ATA or SCSI is better depends on what your needs are, and how much you are willing to spend. In this section I attempt to put the issue in perspective by looking at various performance and quality aspects of the interface and seeing how IDE/ATA and SCSI stack up at each. Of course this will be coloured somewhat by my own experience and biases (the entire web site is--that's just life). However, I am attempting here to be as objective as possible in contrasting the two interfaces, and trying to be comprehensive in looking at all of the aspects that are relevant to making a decision.

A primary deciding factor in the SCSI vs. IDE/ATA question is the number of devices you plan to use (or use in the future) in your system. In many respects, IDE/ATA is superior if you are using only one, two or three devices such as hard disks or CD-ROMs. If you are using many devices, say over four, then SCSI is superior to IDE/ATA in several different respects. Many times people make the decision about what interface to use based on what interface they began with; few are willing to buy all new devices in making an interface switch. Of course, it's quite possible to use both interfaces in the same system.