[ The PC Guide | Systems and Components Reference Guide | Hard Disk Drives | Hard Disk Interfaces and Configuration | IDE/ATA vs. SCSI: Interface Comparison ]

System Resource Usage

Generally speaking, SCSI is superior to IDE/ATA in terms of how many system resources are used. If you are only using a single IDE/ATA channel, the two are basically a wash in terms of resource usage. However, once you go to a dual IDE channel situation you will generally consume more resources than SCSI uses--and most PCs have dual channels by default, unless you disable one. If you were ever to set up a four-channel IDE implementation you would be using significantly more resources than if you had just set up a SCSI bus.

There are in fact some people who set up SCSI specifically to get around the system resource constraints for which the PC is "famous", and which using multiple IDE/ATA channels exacerbates. Doing this also allows you to worry less about needing to take more resources in the future if you expand to many different devices.

There is one system resource issue involved in using SCSI under DOS or Windows 3.x, however, that doesn't apply to newer Windows operating systems. Both of the older operating systems generally require a driver in order to use SCSI, which can take up a decent-sized chunk of conventional or upper memory. The IDE interface does not normally have this requirement. This is only an issue for some systems, of course, and the importance of conventional memory has diminished somewhat today, as those older operating systems are less and less used.

Next: Support for Non-PC Platforms

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