Fujitsu MHN2100AT - Mobile 10 GB Hard Drive, Product Manual

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5.4 Command Protocol
C141-E120-02EN 5-93
The execution of these commands includes the transfer one or more sectors of
data from the host to the device. In the WRITE LONG command, 516 bytes are
transferred. Following shows the protocol outline.
a) The host writes any required parameters to the Features, Sector Count, Sector
Number, Cylinder, and Device/Head registers.
b) The host writes a command code in the Command register. The drive sets the
BSY bit of the Status register.
c) When the device is ready to receive the data of the first sector, the device sets
DRQ bit and clears BSY bit.
d) The host writes one sector of data through the Data register.
e) The device clears the DRQ bit and sets the BSY bit.
f) When the drive completes transferring the data of the sector, the device clears
BSY bit and asserts INTRQ signal. If transfer of another sector is requested,
the drive sets the DRQ bit.
g) After detecting the INTRQ signal assertion, the host reads the Status register.
h) The device resets INTRQ (the interrupt signal).
i) If transfer of another sector is requested, steps d) and after are repeated.
Figure 5.5 shows an example of WRITE SECTOR(S) command protocol.