Logical Chs Addressing Mode; Lba Addressing Mode; Overlapped And Queued Feature - IBM DTTA-351010 - Deskstar 10.1 GB Hard Drive Specifications

10.3.1 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 translation mode
but can not exceed 255(0FFh). Heads are numbered from 0 to the maximum value allowed by the current
CHS translation mode buf can not exceed 15(0Fh). Cylinders are numbered from 0 to the maximum value
allowed by the current CHS translation mode but cannot exceed 65535(0FFFFh).
When the host selects a CHS translation mode using the INITIALIZE DEVICE PARAMETERS
command, the host requests the number of sectors per logical track and the number of heads per logical
cylinder. The device then computes the number of logical cylinders available in requested mode.
The default CHS translation mode is described in the Identify Device Information. The current CHS trans-
lation mode also is described in the Identify Device Information.

10.3.2 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). Irrespective 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.
Device/Head <---
Cylinder High <---
Cylinder Low <---
Sector Number <---

10.4 Overlapped and Queued Feature

Overlap allows devices to perform a bus release so that the other device on the bus may be used. To
perform a bus release the device clears both D R Q and BSY to zero. When selecting the other device during
overlapped operations, the host shall disable interrupts via the nIEN bit on the currently selected device
before writing the Device/Head register to select the other device.
The only commands that may be overlapped are:
NOP (with 01h subcommand code)
Read DMA Queued
Service
Write DMA Queued
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O E M Specifications for DTTA-3xxxxx
LBA bits 27-24
LBA bits 23-16
LBA bits 15- 8
LBA bits 7- 0
('00'h)
('C7'h)
('A2'h)
('CC'h)