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INTERFACE COMMANDS
7 – 12
Initialize Drive Parameters
Enables the drive to operate as any logical drive type. The drive will always be in the translate mode because
of Zone Density Recording, which varies the number of sectors per track depending on the zone.
Through setting the Sector Count Register and Drive Head Register, this command lets the host alter the
drive's logical configuration. As a result, the drive can operate as any equal to or less than capacity drive type.
Do not exceed the total number of sectors available on the drive:
When this command is executed, the drive reads the Sector Counter Register and the Drive Head Register
(and so determines the number of the logical sectors per track and maximum logical head number per
cylinder and will calculate the number of logical cylinders.)
Upon receipt of the command, the drive:
1. Sets BSY,
2. Saves the parameters,
3. Resets BSY and
4. Generates an interrupt.
To specify maximum heads, write 1 less than the maximum (e.g. write 4 for a 5 head drive). To specify
maximum sectors, specify the actual number of sectors (e.g. 17 for a maximum of 17 sectors/track).
The sector count and head values are not checked for validity by this command. If they are invalid, no error
will be posted until an illegal access is made by some other command.
Moves the read/write heads from anywhere on the disk to cylinder 0.
When this command is received, the drive:
1. Sets BSY and
2. Issues a seek to cylinder zero.
The drive waits for the seek to complete, then the drive:
1. Updates status,
2. Resets BSY and
3. Generates an interrupt.
If the drive cannot reach cylinder 0, the Error bit is set in the Status register, and the Track 0 bit is set in the
Error register.
NOTE: If a maximum head and sector number is selected – such that the number of cylinders will exceed 65,535 – then
the maximum cylinder value will be reduced to 65, 535.