)
Values for SMARTDRV function code:
 00h	flush cache
 01h	flush and discard cache
 02h	disable caching (flushes and discards cache first)
 03h	enable caching
 04h	control write caching
 05h	set flushing tick count
 06h	lock cache contents
 07h	unlock cache contents
 08h	set flush-on-reboot flag
 09h	unused
 0Ah	control full-track caching
 0Bh	reduce cache size
 0Ch	increase cache size
 0Dh	set INT 13 chain address