Fujitsu MHW2040AC User Manual download pdf (Page 252)

Operations

6.4 Read-ahead Cache

Read-ahead Cache is the function for automatically reading data blocks upon

completion of the read command in order to read data from disk media and save

data block on a data buffer.

If a subsequent command requests reading of the read-ahead data, data on the data

buffer can be transferred without accessing the disk media. As the result, faster

data access becomes possible for the host.

6.4.1 DATA buffer structure

This device contains a data buffer. This buffer is divided into two areas: one area

is used for MPU work, and the other is used as a read cache for another command.

(See Figure 6.7)

8MB buffer (8,388,608 bytes)

For MPU work For R/W command

8,388,608 bytes

Figure 6.7 Data buffer structure

The read-ahead operation is done by the following commands.

• READ SECTOR(S) (EXT)

• READ MULTIPLE (EXT)

• READ DMA (EXT)

• READ SECTOR(S) EXT

• READ DMA EXT

• READ MULTIPLE EXT

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Fujitsu MHW2040AC User Manual Page 252