Int 14 Fn 4008  - I1541 - Send Secondary Address For Talk                  [t]

   AX = 4008h
   BL = channel number and mode (see #0281)

Return: CF clear if successful
   CF set on error
       AL = error number (see also #0280)
       40h turn around time-out

See Also: AX=4007h,AX=4009h