Datasheet

12.4.3 Required power-off sequence

Problems can occur on most drives when the power is removed at an arbitrary time. The following are

some examples of arbitrary power-off occurrence:

y Data loss from the write buffer

y If the drive is writing a sector and a partially-written sector with an incorrect ECC block results. The

sector contents are destroyed and reading the partially-written sector results in a hard error

y Depending on the design of the drive, the heads may possibly land in the data zone instead of the

landing zone

You may then turn off the drive in the following order:

1. Issue a STANDBY IMMEDIATE command

2. Wait until Command Complete Status is returned (It may take up to 350 ms in typical case)

3. Terminate power to the drive

This power-down sequence should be followed for entry into any system power-down state, or system

suspend state, or system hibernation state. In a robustly designed system, emergency unload is limited to

rare instancess such as battery removal during operation.

12.5 Sector Addressing Mode

12.5.1 Logical CHS Addressing Mode

The logical CHS addressing is made up of three fields: the cylinder number, the head number, and the

sector number. Sectors are numbered from 1 to the maximum value allowed by the current CHS trans-

lation mode and can not exceed 255 (0FFh). Heads are numbered from 0 to the maximum value allowed

by the current CHS translation mode and can not exceed 15 (0Fh). Cylinders are numbered from 0 to the

maximum value allowed by the current CHS translation mode and cannot exceed 65535 (0FFFFh).

When the host selects a CHS translation mode using the INITIALIZE DRIVE PARAMETERS command,

the host requests the number of sectors per logical track and the number of heads per logical cylinder. In

requested mode the device computes the number of logical cylinders available.

The current CHS translation mode, as well as the default CHS translation mode, is returned by the

Identify Device Information as shown in figure 82 on page 97.

12.5.2 LBA Addressing Mode

Logical sectors on the device shall be linearly mapped with the first LBA addressed sector (sector 0)

being the same sector as the first logical CHS addressed sector ( cylinder 0, head 0, sector 1). Irre-

spective of the logical CHS translation mode currently in effect, the LBA address of a given logical sector

does not change. The following is always true:

LBA = ( (cylinder * heads_per_cylinder + heads) * sectors_per_track ) + sector – 1

where heads_per_cylinder and sectors_per_track are the current translation mode values.

On LBA addressing mode, the LBA value is set to the following register:

7–0LBA bits

Sector Number

15–8LBA bits

Cylinder Low

23–16LBA bits

Cylinder High

27–24LBA bits

Device/Head

Hard disk drive specification for DSCM-11000/-10512/-10340