7 (-CE1)
31 (-CE2)
-CE1
-CE2
-CE1
-CE2
-CS0
-CS1
Notes:1) The UDMA interpretation of this signal is valid only during an Ultra DMA data burst.
2) The UDMA interpretation of this signal is valid only during and Ultra DMA data burst during a DMA Read command.
3) The UDMA interpretation of this signal is valid only during an Ultra DMA data burst during a DMA Write command.
4) The HSTROBE and DSTROBE signals are active on both the rising and the falling edge.
5) Address lines 03 through 10 are not used in True IDE mode.
Several signal lines are redefined to provide different functions during an Ultra DMA data burst. These lines assume their
UDMA definitions when:
1 an Ultra DMA mode is selected, and
2 a host issues a READ DMA, or a WRITE DMA command requiring data transfer, and
3 the device asserts (-)DMARQ, and
4 the host asserts (-)DMACK.
These signal lines revert back to the definitions used for non-Ultra DMA transfers upon the negation of -DMACK by the host at
the termination of an Ultra DMA data burst.
With the Ultra DMA protocol, the STROBE signal that latches data from D[15:00] is generated by the same agent (either host
or device) that drives the data onto the bus. Ownership of D[15:00] and this data strobe signal are given either to the device
during an Ultra DMA data-in burst or to the host for an Ultra DMA data-out burst.
During an Ultra DMA data burst a sender shall always drive data onto the bus, and, after a sufficient time to allow for
propagation delay, cable settling, and setup time, the sender shall generate a STROBE edge to latch the data. Both edges of
STROBE are used for data transfers so that the frequency of STROBE is limited to the same frequency as the data.
Words in the IDENTIFY DEVICE data indicate support of the Ultra DMA feature and the Ultra DMA modes the device is
capable of supporting. The Set transfer mode subcommand in the SET FEATURES command shall be used by a host to
select the Ultra DMA mode at which the system operates. The Ultra DMA mode selected by a host shall be less than or equal
to the fastest mode of which the device is capable. Only one Ultra DMA mode shall be selected at any given time. All timing
requirements for a selected Ultra DMA mode shall be satisfied. Devices supporting any Ultra DMA mode shall also support all
slower Ultra DMA modes.