Int 13 Fn 2D  u - Quickcache Ii V4.20 - Set Buffered Read                  [c]

   AH = 2Dh
   AL = new state (00h disabled, 01h enabled)

Return: AX = status (0000h successful)
Desc:  specify whether the cache should attempt to read ahead of actual
     requests

Note:  this function enables or disables read-ahead for all drives; use AH=37h
     to change a single drive

See Also: AH=2Ch,AH=37h