FUJITSU M3093DG - Manual (Page 51)

After the ACK signal is false, the target may continue the transfer by driving
the DB(7>0, P) signals and asserting the REQ signal, as previously described.
deskew delay +
cable skew delay
deskew delay
+ cable skew delay
bus settle delay
BSY
SEL
C/D, MSG
REQ
ACK
DB
I/O
b. Asynchronous transfer from initiator to target
If the I/O signal is false (transfer to the target), the target shall request
information by asserting the REQ signal. The initiator shall drive the DB(7>0,
P) signals to their desired values, delay at least one deskew delay plus a cable
skew delay then assert the ACK signal. The initiator shall continue to drive the
DB(7>0, P) signals until the REQ signal is false. When the ACK signal becomes
true at the target, the target shall read the DB(7>0, P) signals then negate the
REQ signal. When the REQ signal becomes false at the initiator, the initiator
may change or release the DB(7>0, P) signals and shall negate the ACK signal.
The target may continue the transfer by asserting the REQ signal, as previously
described.
4 $ 19