Fujitsu MHW2040AC User Manual download pdf (Page 139)

5.3 Host Commands

(18) READ MULTIPLE (X’C4’)

The READ MULTIPLE Command performs the same as the READ SECTOR(S)

Command except that when the device is ready to transfer data for a block of

sectors, and enters the interrupt pending state only before the data transfer for the

first sector of the block sectors. In the READ MULTIPLE command operation,

the DRQ bit of the Status register is set only at the start of the data block, and is

not set on each sector.

The number of sectors per block is defined by a successful SET MULTIPLE

MODE Command. The SET MULTIPLE MODE command should be executed

prior to the READ MULTIPLE command.

If the number of requested sectors is not divided evenly (having the same number

of sectors [block count]), as many full blocks as possible are transferred, then a

final partial block is transferred. The number of sectors in the partial block to be

transferred is n where n = remainder of (“number of sectors”/”block count”).

If the READ MULTIPLE command is issued before the SET MULTIPLE MODE

command is executed or when the READ MULTIPLE command is disabled, the

device rejects the READ MULTIPLE command with an ABORTED COMMAND

error.

Figure 5.2 shows an example of the execution of the READ MULTIPLE

command.

• Block count specified by SET MULTIPLE MODE command = 4 (number of

sectors in a block)

• READ MULTIPLE command specifies;

Number of requested sectors = 9 (Sector Count register = 9)

Figure 5.2 Execution example of READ MULTIPLE command

C141-E258 5-63

1 2 ... 134 135 136 137 138 139 140 141 142 143 144 ... 277 278

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Fujitsu MHW2040AC User Manual Page 139