Int 2F Fn D111 - Mdebug Command Driver - Start Driver [G]
AX = D111h
Return: DL = FFh
Notes: only called by the transient part of the driver to inform the resident
part that it is installed
the function must be reentrant and the driver mustn't chain this
function to the old INT 2F
See Also: AX=D101h,AX=D112h