User's Guide

Page 12 DDS-4 SCSI Interface Manual, Rev. B
t
3
The Initiator reads the data and parity signals after REQ is
asserted and then signals its acceptance of the data by asserting
the ACK.
t
4
ACK goes low at the Target, and the Target de-asserts REQ.
t
5
The REQ signal is false. The Initiator de-asserts ACK. After the
ACK signal is high, the Target can continue the transfer by
repeating the steps from t
1
.
Figure 2-4
Signals Used in Transfer from Target to Initiator
Transfer from Initiator to Target
Transfer from Initiator to Target is described in the following table and illustrated in
Figure 2-5.
Timing Point Action
t
1
The I/O signal is de-asserted, and the Target asserts REQ to
request information.
t
2
The Initiator drives the data and parity signals to their desired
values.
t
3
The Initiator asserts the ACK.
t
4
The Target de-asserts REQ, signaling its acceptance of data.
The Initiator then releases the data and parity signals.
t
5
The Initiator de-asserts ACK. The Target can then continue to
transfer by asserting the REQ signal.