DOS
Cmd Name Ver. Usage Flags
On entry to the Strategy routine (see Device Driver Basics), DOS passes
the address of a request structure in ES:BX (see DevRequestHdrRec). The
bCmd field of that structure (at offset 2) will contain one of the above
command codes.
The variable-length data that follows the DevRequestHdrRec varies from
command to command. Some commands share identical request structures.
Others have a unique structure and some use only the request header to
communicate with DOS.
See Also: IOCTL Functions
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