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C141-E034-02EN 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.