INT 2F - DR-DOS 6.0 TaskMAX - NAME TASK
        AX = 2709h
        DX = task index
        DS:SI -> 8-byte name (8 NULs = remove name)
Return: AL = task flags
            00h ID unused or task terminated
            01h ID in use, task name table entry valid
            81h ID in use, task name fixed
        BX = task ID
        ES:DI -> name in task name table (see AX=2701h)
Note:   the task retains the given name until it terminates or the name is
          removed by specifying a name of 8 NULs.
SeeAlso: AX=2707h