Quantum DLTtape DLT 7000, Product Manual

Page: 84 / 312

SCSI Description
3-20 Quantum DLT 7000 Tape System
3.5.5.1 Asynchronous Data Transfer
Drive to Initiator Transfer Procedure
1. The drive drives the DB (0-15, P, & P1) signals to their desired values.
2. Drive delays at least one deskew delay plus a cable skew delay.
3. Drive asserts the REQ signal.
4. Initiator reads the DB (0-15, P, & P1) signals.
5. Initiator indicates its acceptance of the data by asserting the ACK signal.
6. When ACK is true at the drive, drive can change or release the DB (0-15,
P, & P1) signals.
7. Drive negates the REQ signal.
8. Initiator negates the ACK signal.
9. Drive can continue the transfer by driving the DB (0-15, P, & P1) signals
and asserting the REQ signal (Steps 1 – 3).
Initiator-to-Drive Transfer Procedure
1. Drive asserts the REQ signal.
2. Initiator drives the DB (0-15, P, & P1) signals to their desired values.
3. Initiator delays at least one deskew delay plus a cable skew delay.
4. Initiator asserts the ACK signal.
5. When ACK is true at the drive, drive reads the DB (0-15, P, & P1)
signals.
6. Drive negates the REQ signal.
7. Initiator can change or release the DB (0-15, P, & P1) signals.
8. Initiator negates the ACK signal.
9.
Drive can continue the transfer by asserting the REQ signal (Step 1).