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

Expandability and Number of Devices

On this particular score there isn't much of a competition: SCSI beats IDE/ATA hands down. While SCSI is more involved and expensive to set up, once you make the appropriate investments of money and time you get a bus that can be expanded relatively easily to either 7 devices (with narrow SCSI) or 15 (with wide SCSI, which is what most new systems use). On the other hand, IDE/ATA normally supports only four devices; you can expand this to eight if you add an after-market IDE/ATA controller, but that can introduce its own issues.

Of course, this advantage of SCSI only matters if you actually need this much expansion capability. For most users, four device expandability is certainly sufficient, and eight is definitely more than enough.

Next: Device Type Support

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