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10.8.17 Set Multiple Mode (C6h)
COMMAND CODE
1 1 0 0 0 1 1 0
REGISTER
REGISTER SETTING NORMAL COMPLETION
DR drive no. no change
CY no change
HD no change
SN no change
SC The number of sectors / block no change
FT no change
This command enables the drive to perform Read and Write Multiple operations and sets the block count for
these commands.
The Sector Count Register is loaded with the number of sectors per block. The drive supports 1,2,4,8 or16
sectors per block.
Upon receipt of the command, the drive sets BSY=1 and checks the content of Sector Count Register.
If the Sector Count Register contains a valid value and the block count is supported, the value is loaded for
all subsequent Read Multiple and Write Multiple commands. And these commands are enabled to be
executed. If a block count is not supported , this command shall be terminated with the report of an Aborted
Command error , and Read Multiple and Write Multiple commands are disabled.
If the Sector Count Register contains 0 when the command is issued, Read Multiple and Write Multiple
commands are disabled.
In case of software reset, the result depends on the setting of Set Feature command. If FT=66h, the mode
is not changed. If FT = CCh, the mode reverts to power on default (16 sectors).
10.8.18 Read DMA (C8h/C9h)
COMMAND CODE
1 1 0 0 1 0 0 X
REGISTER
REGISTER SETTING NORMAL COMPLETION
DR drive no. no change
CY starting cylinder last possible
HD starting head last possible
SN starting sector last possible
SC no. of sector to read 00H
FT no change
LBA staring address last address
This command is basically identical to Sector command except following features.
•
Host initialize slave-DMA channel before issuing command.
- Data transfer is initiated by DMARQ and handled by slave-DMA channel in the host.
- Drive issues only one interrupt at the completion of each command to show the status is valid after data
transfer.
During DMA transfer phase, either BSY or DRQ is set to 1.
When a command is completed, CY, HD, SN register (LBA register) shows the sector transferred the latest.
If the drive detects unrecoverable error, the drive terminate the command and CY, HD, SN register (LBA
register) shows the sector where error occurred.