Int 7F Fn 09 - Multilink Advanced V1.0+ - 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
See Also: AH=00h"MultiLink",AH=0Ah"MultiLink"