Maxtor 10K III manual ST and DT CLocking

Maxtor Atlas 10K III 6-11

Feature Descriptions

￿￿￿￿￿￿&6￿With#0&Ultra160￿56￿%.1%and -Ulra320+0)SCSI interfaces, Maxtor has introduced a new method of clocking data on the SCSI bus. This method, called Double Transition (DT) clocking, uses both the rising and falling edges of the REQ and ACK signals to clock data into the receiving device. This has the advantage of allowing the REQ and ACK signals to run at half the frequency that would be required under the traditional Single Transition (ST) SCSI clocking scheme for the same data rate. Lower frequency clocks result in a more reliable bus. Figure 6-1illustrates the difference between DT and ST clocking.

ST and DT CLocking

The Maxtor AtlasFigure10K III6disk-1drive can operate at speeds up to 80 MB/sec in either ST or DT modes, depending on the capabilities of the host adapter. Transfer rates above 80 MB/sec are only supported in DT mode, as required by the SPI-3 SCSI standard.