Hitachi C4K60 Specifications - Page 85

Read Multiple EXT [29h]

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7.5.20. Read Multiple EXT [29h] Task File Register 7 6 5 4 3 2 1 0 Command 29h Feature Previous setting XX Current setting XX LBA High Previous setting LBA bit 47 - 40 Current setting LBA bit 23 - 16 LBA Mid Previous setting LBA bit 39 - 32 Current setting LBA bit 15 - 8 LBA Low Previous setting LBA bit 31 - 24 Current setting LBA bit 7 - 0 Sector Count Previous setting Sector Count bit 15 - 8 Current setting Sector Count bit 7 - 0 Device X 1 X DEV X X X X The READ MULTIPLE EXT command is similar to the READ SECTORS EXT command, except interrupts are not generated on every sector, but on the transfer of a block which contains the number of sectors defined by a SET MULTIPLE MODE command. The number of sectors defined by a SET MULTIPLE MODE command is transferred without intervening interrupts. DRQ qualification of the transfer is required only at the start of the data block, not on each sector. The SET MULTIPLE MODE command, which must be executed prior to the READ MULTIPLE EXT command, sets the block count of sectors to be transferred. When the READ MULTIPLE EXT command is issued, the Sector Count Register contains the number of sectors (not the number of blocks or the block count) requested. If the number of requested sectors is not evenly divisible by the block count, as many full blocks as possible are transferred, followed by a final, partial block transfer for n sectors, where n = residue of {Sector Count / Sector Count per Block}. Disk errors encountered during READ MULTIPLE EXT commands are posted at the beginning of the block or partial block transfer, but DRQ is still set and the data transfer should be executed as it normally would, including transfer of corrupted data, if any. Subsequent blocks or partial blocks are transferred only if the error was a correctable data error. All other errors cause the command to stop after transfer of the block that contained the error. Interrupts are generated when DRQ is set at the beginning of each block or partial block. K6610170 Rev.2 Dec 22, 2004 - 85 -

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K6610170
Rev.2
Dec 22, 2004
- 85 -
7.5.20. Read Multiple EXT [29h]
Task File Register
7
6
5
4
3
2
1
0
Command
29h
Feature
Previous setting
XX
Current setting
XX
LBA High
Previous setting
LBA bit 47 - 40
Current setting
LBA bit 23 - 16
LBA Mid
Previous setting
LBA bit 39 - 32
Current setting
LBA bit 15 - 8
LBA Low
Previous setting
LBA bit 31 - 24
Current setting
LBA bit 7 - 0
Sector Count
Previous setting
Sector Count bit 15 - 8
Current setting
Sector Count bit 7 - 0
Device
X
1
X
DEV
X
X
X
X
The READ MULTIPLE EXT command is similar to the READ SECTORS EXT command, except interrupts
are not generated on every sector, but on the transfer of a block which contains the number of sectors
defined by a SET MULTIPLE MODE command. The number of sectors defined by a SET MULTIPLE MODE
command is transferred without intervening interrupts. DRQ qualification of the transfer is required only at
the start of the data block, not on each sector. The SET MULTIPLE MODE command, which must be
executed prior to the READ MULTIPLE EXT command, sets the block count of sectors to be transferred.
When the READ MULTIPLE EXT command is issued, the Sector Count Register contains the number of
sectors (not the number of blocks or the block count) requested. If the number of requested sectors is not
evenly divisible by the block count, as many full blocks as possible are transferred, followed by a final, partial
block transfer for n sectors, where n = residue of {Sector Count / Sector Count per Block}.
Disk errors encountered during READ MULTIPLE EXT commands are posted at the beginning of the block
or partial block transfer, but DRQ is still set and the data transfer should be executed as it normally would,
including transfer of corrupted data, if any. Subsequent blocks or partial blocks are transferred only if the
error was a correctable data error. All other errors cause the command to stop after transfer of the block that
contained the error. Interrupts are generated when DRQ is set at the beginning of each block or partial block.