[ The PC Guide | Systems and Components Reference Guide | Hard Disk Drives | Hard Disk Interfaces and Configuration | Integrated Drive Electronics / AT Attachment (IDE/ATA) Interface | IDE/ATA Transfer Modes and Protocols ]

Block Mode

On some systems you will find an option in the system BIOS called block mode. Block mode is a performance enhancement that allows the grouping of multiple read or write commands over the IDE/ATA interface so that they can be handled on a single interrupt.

Interrupts are used to signal when data is ready to be transferred from the hard disk; each one, well, interrupts other work being done by the processor. Newer drives, when used with a supporting BIOS allow you to transfer as many as 16 or 32 sectors with a single interrupt. Since the processor is being interrupted much less frequently, performance is much improved, and more data is moving around with less command overhead, which is much more efficient than transferring data one sector at a time.

Note: Some systems can have trouble running disks in block mode, even if they are supposed to allow it. You may have better luck with the drive or system if it is disabled.

Next: IDE/ATA Configuration and Cabling

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