Fujitsu MHW2040AT - Mobile 40 GB Hard Drive, Product Manual, Page: 205 / 278

5.4 Command Protocol
For transfer of a sector of data, the host needs to read Status register
(X’1F7’) in order to clear INTRQ (interrupt) signal. The Status
register should be read within a period from the DRQ setting by the
device to starting of the sector data transfer. Note that the host does
not need to read the Status register for the reading of a single sector
or the last sector in multiple-sector reading. If the timing to read the
Status register does not meet above condition, normal data transfer
operation is not guaranteed.
When the host new command even if the device requests the data
transfer (setting in DRQ bit), the correct device operation is not
guaranteed.
(*) Transfers dummy data
Figure 5.4 Protocol for command abort
C141-E250 5-131