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C141-E045-02EN 5 - 35
The host sets X'03' to the Features register. By issuing this command with setting a value to
the Sector Count register, the transfer mode can be selected. Upper 5 bits of the Sector Count
register defines the transfer type and lower 3 bits specifies the binary mode value.
However, the IDD can operate with the PIO transfer mode 4 and multiword DMA transfer
mode 2 regardless of reception of the SET FEATURES command for transfer mode setting.
The IDD supports following values in the Sector Count register value. If other value than
below is specified, an ABORTED COMMAND error is posted.
PIO default transfer mode 00000 000 (X‘00’)
PIO flow control transfer mode X 00001 000 (X‘08’: Mode 0)
00001 001 (X‘09’: Mode 1)
00001 010 (X‘0A’: Mode 2)
00001 011 (X‘0B’: Mode 3)
00001 100 (X‘0C’: Mode 4)
Single word DMA transfer mode X 00010 000 (X‘10’: Mode 0)
00010 001 (X‘11’: Mode 1)
00010 010 (X‘12’: Mode 2)
Multiword DMA transfer mode X 00100 000 (X‘20’: Mode 0)
00100 001 (X‘21’: Mode 1)
00100 010 (X‘22’: Mode 2)
Ultra DMA transfer mode X 01000 000 (X‘40’: Mode 0)
01000 001 (X‘41’: Mode 1)
01000 010 (X‘42’: Mode 2)
(15) SET MULTIPLE MODE (X'C6')
This command enables the device to perform the READ MULTIPLE and WRITE MULTIPLE
commands. The block count (number of sectors in a block) for these commands are also
specified by the SET MULTIPLE MODE command.
The number of sectors per block is written into the Sector Count register. The IDD supports 2,
4, 8, 16 and 32 (sectors) as the block counts.
Upon receipt of this command, the device sets the BSY bit of the Status register and checks
the contents of the Sector Count register. If the contents of the Sector Count register is valid
and is a supported block count, the value is stored for all subsequent READ MULTIPLE and
WRITE MULTIPLE commands. Execution of these commands is then enabled. If the value
of the Sector Count register is not a supported block count, an ABORTED COMMAND error
is posted and the READ MULTIPLE and WRITE MULTIPLE commands are disabled.
If the contents of the Sector Count register is 0 when the SET MULTIPLE MODE command
is issued, the READ MULTIPLE and WRITE MULTIPLE commands are disabled.
When the SET MULTIPLE MODE command operation is completed, the device clears the
BSY bit and generates an interrupt.