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IDE Solid State Disk
(18) Write DMA – CAh
Bit ->
7
Command (7)
1
C/D/H (6)
Cyl High (5)
Cyl Low (4)
Sec Num (3)
Sec Cnt (2)
Feature (1)
This command uses DMA mode to write from 1 to 256 sectors as specified in the Sector Count register. A sector count
of 0 requests 256 sectors. The transfer begins at the sector specified in the Sector Number Register. When this
command is issued the device sets BSY, puts all or part of the sector of data in the buffer. The Card is then permitted,
although not required, to set DRQ, clear BSY. The Card asserts DMAREQ while data is available to be transferred.
The host then writes the (512 * sector-count) bytes of data to the Card using DMA. While DMAREQ is asserted by the
Card, the Host asserts -DMACK while it is ready to transfer data by DMA and asserts -IOWR once for each 16 bit word
to be transferred from the Host.
Interrupts are not generated on every sector, but upon completion of the transfer of the entire number of sectors to be
transferred or upon the occurrence of an unrecoverable error.
At command completion, the Command Block Registers contain the cylinder, head and sector number of the last
sector read. If an error occurs, the read terminates at the sector where the error occurred. The Command Block
Registers contain the cylinder, head, and sector number of the sector where the error occurred. The amount of data
transferred is indeterminate.
When a Write DMA command is received by the Card and 8 bit transfer mode has been enabled by the Set Features
command, the Card shall return the Aborted error.
(19) Write Multiple Command - C5h
Bit ->
7
Command (7)
1
C/D/H (6)
Cyl High (5)
Cyl Low (4)
Sec Num (3)
Sec Cnt (2)
Feature (1)
This specification requires that devices support a multiple block count of 1 and permits larger values to be supported.
Notice:
This command is similar to the Write Sectors command. The device sets BSY within 400 nsec of accepting the
command. Interrupts are not presented on each sector but on the transfer of a block that contains the number of
sectors defined by Set Multiple. Command execution is identical to the Write Sectors operation except that the number
of sectors defined by the Set Multiple 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 block count of
sectors to be transferred without intervening interrupts is programmed by the Set Multiple Mode command, which shall
be executed prior to the Write Multiple command.
When the Write Multiple 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. The partial block
transfer is for n sectors, where:
n = (sector count) modulo (block count).
If the Write Multiple command is attempted before the Set Multiple Mode command has been executed or when Write
Rev. A.6
6
5
LBA
1
Cylinder High (LBA 23-16)
Cylinder Low (LBA 15-8)
Sector Number (LBA 7-0)
Write DMA
6
5
LBA
1
Write Multiple Command
26/32
4
3
CAh
Drive
Sector Count
X
4
3
C5h
Drive
Cylinder High
Cylinder Low
Sector Number
Sector Count
X
2
1
Head (LBA 27-24)
2
1
Head
Nov. 2008
0
0
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