)
Values for PS/1 hard disk feature number:
 01h	select 8-bit data transfers instead of 16-bit
 02h	enable write cache
 22h	Write Same, user-specified area
 33h	disable retries
 44h	set number of ECC bytes for read long/write long (see AH=0Ah,AH=0Bh)
 54h	set cache segments
 55h	disable lookahead
 66h	disable reverting to power-on defaults
 77h	disable error correctioni
 81h	select 16-bit data transfers (default)
 82h	disable write cache
 88h	enable error correction (default)
 99h	enable retries (default)
 AAh	enable lookahead
 BBh	set ECC length for read long/write long to four bytes
 CCh	enable reverting to power-on defaults
 DDh	Write Same, entire disk
SeeAlso: #P0535