IBM DTTA-351010 Hard Drive Specifications - Page 84

Overlapped and Queued Feature

Get IBM DTTA-351010 - Deskstar 10.1 GB Hard Drive PDF manuals and user guides View all IBM DTTA-351010 manuals
Add to My Manuals
Save this manual to your list of manuals

Page 84 highlights

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 translation 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

  • 1
  • 2
  • 3
  • 4
  • 5
  • 6
  • 7
  • 8
  • 9
  • 10
  • 11
  • 12
  • 13
  • 14
  • 15
  • 16
  • 17
  • 18
  • 19
  • 20
  • 21
  • 22
  • 23
  • 24
  • 25
  • 26
  • 27
  • 28
  • 29
  • 30
  • 31
  • 32
  • 33
  • 34
  • 35
  • 36
  • 37
  • 38
  • 39
  • 40
  • 41
  • 42
  • 43
  • 44
  • 45
  • 46
  • 47
  • 48
  • 49
  • 50
  • 51
  • 52
  • 53
  • 54
  • 55
  • 56
  • 57
  • 58
  • 59
  • 60
  • 61
  • 62
  • 63
  • 64
  • 65
  • 66
  • 67
  • 68
  • 69
  • 70
  • 71
  • 72
  • 73
  • 74
  • 75
  • 76
  • 77
  • 78
  • 79
  • 80
  • 81
  • 82
  • 83
  • 84
  • 85
  • 86
  • 87
  • 88
  • 89
  • 90
  • 91
  • 92
  • 93
  • 94
  • 95
  • 96
  • 97
  • 98
  • 99
  • 100
  • 101
  • 102
  • 103
  • 104
  • 105
  • 106
  • 107
  • 108
  • 109
  • 110
  • 111
  • 112
  • 113
  • 114
  • 115
  • 116
  • 117
  • 118
  • 119
  • 120
  • 121
  • 122
  • 123
  • 124
  • 125
  • 126
  • 127
  • 128
  • 129
  • 130
  • 131
  • 132
  • 133
  • 134
  • 135
  • 136
  • 137
  • 138
  • 139
  • 140
  • 141
  • 142
  • 143
  • 144
  • 145
  • 146
  • 147
  • 148
  • 149
  • 150
  • 151
  • 152
  • 153
  • 154
  • 155
  • 156
  • 157
  • 158
  • 159
  • 160
  • 161
  • 162
  • 163
  • 164
  • 165
  • 166
  • 167
  • 168
  • 169
  • 170
  • 171
  • 172
  • 173
  • 174
  • 175
  • 176
  • 177
  • 178
  • 179
  • 180
  • 181
  • 182
  • 183
  • 184
  • 185
  • 186
  • 187
  • 188
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
<---
LBA bits 27-24
Cylinder High
<---
LBA bits 23-16
Cylinder Low
<---
LBA bits 15- 8
Sector Number
<---
LBA bits 7- 0
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 DRQ 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)
('00'h)
Read DMA Queued
('C7'h)
Service
('A2'h)
Write DMA Queued
('CC'h)
76
OEM Specifications for DTTA-3xxxxx