Seagate Ultra 320, Ultra 160 manual Paced transfer on a Scsi bus, DT synchronous transfer example

transfer period = 25 ns

25 ns 25 ns 25 ns

REQ or ACK

DT Data

DT	DT	DT	DT
Clock	Clock	Clock	Clock

Example: A negotiated transfer period of 25 ns equates to a transfer rate of 40 megatransfers per second.

Figure 7. DT synchronous transfer example

transfer period = 6.25 ns

6.25 ns 6.25 ns 6.25 ns

REQ or ACK

DT Data

DT	DT	DT	DT
Clock	Clock	Clock	Clock

Example: A negotiated transfer period of 6.25 ns equates to a transfer rate of 160 megatransfers per second.

Figure 8. Paced transfer example

2.8Paced transfer on a SCSI bus

A SCSI bus that supports paced transfers has additional driver and receiver functions required over those used with synchronous transfers or asynchronous transfers. These functions include driver precompensation, receiver skew compensation, receiver clock shifting, and an optional receiver signal adjustment. In addition, the drive precompensation may be switched out of the data path at the request of the receiving SCSI device.

36 Parallel SCSI Interface Product Manual, Rev. A )