Samsung 3.5" hard disk drives, spinpoint v40 6.7 Timing

DISK DRIVE OPERATION
SpinPoint V40 Product Manual 89
6.7 Timing
The minimum cycle time supported by the device in PIO mode 3, 4 and Multiword DMA mode 1, 2
respectively, shall always be greater than, or equal to the minimum cycle time defined by the associated
mode. For example, a device supporting PIO mode 4 timing shall not report a value less than 120ns, the
minimum cycle time defined for PIO mode 4 timings.
6.7.1 Register transfers
Figure 6-1 defines the relationships between the interface signals for register transfers. Peripherals reporting
support for PIO mode 3 or 4 shall power up in a PIO mode 0, 1, or 2.
For PIO modes 3 and above, the minimum value of t0 is specified by word 68 in the IDENTIFY DEVICE
parameter list. Table 6-16 defines the minimum value that shall be placed in word 68.
IORDY will be supported when PIO modes 3 or 4 are the current mode of operation.
NOTE − Some devices implementing the PACKET Command feature set prior to this
standard power up in PIO mode 3 and enable IORDY as the default.