19h DV$LKUP lookup a device vector for a given procedure
Input X register - address of name string.
Output A register - device number.
B register - vector number.
Description This service will call the LANGUAGE vector of all devices in memory and pass them the value in the X register. If a device signals that it is prepared to handle the procedure whose name is pointed to by the X register then the service will return with the A register containing the device number and the B register containing the vector number of the code to handle the procedure.
Example To determine the device number and vector number of the RS232 service which is prepared to handle the LINPUT$ procedure the following code fragment can be used.
        LDX     #LINPUT_NAME            ; POINT TO LINPUT$
        OS      DV$LKUP                 ; SEARCH FOR RS232 DEVICE
        BCS     ERROR                   ; UNABLE TO HANDLE LINPUT$
        STD     LVECT                   ; SAVE A&B FOR LATER USE
        RTS                             ; WITH DV$VECT
        ASCIC   "LINPUT$"
LVECT:  DW      0
Errors 230 - device not present.