Information Technology Reference
In-Depth Information
Figure 11-2: Commands used by a Windows host after enumerating a flash
drive. (Screen capture from Ellisys USB Explorer.)
pleting enumeration. These requests and commands are typical for Win-
dows XP, but hosts aren't required to use this exact sequence:
Get Max LUN. This USB class-specific request asks for the highest LUN
number supported by the device. Devices with single LUNs are the only
ones allowed to stall this request. The host can use the commands below to
initialize communications with each logical unit from zero up to the value
returned.
INQUIRY. The host requests 36 bytes of data about a logical unit.
READ FORMAT CAPACITIES. The host requests a structure containing
one or more descriptors that specify a number of blocks and a block length
that the media can be formatted for.
READ CAPACITY(10). The host requests the highest LBA supported by
the logical unit and the number of bytes in that logical block (typically 512).
READ(10). The host reads sector zero, which should be either an MBR sec-
tor with a partition table or a FAT boot sector (assuming the volume is for-
matted for a FAT file system).
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