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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 t
0
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.