Int 7F Fn 09  - Multilink Advanced - Set Task Priority                     [T]

   AH = 09h
   AL = priority (0-7)

Note:  the installation check consists of ensuring that the interrupt vector
     is not pointing at segment 0000h, then checking whether the byte
     at offset 0000h in the interrupt handler's segment is E9h
Index: installation check;MultiLink Advanced