ON COM
======

Function
--------

**ON COM** defines a routine to be executed when data is received into
the communications buffer.

Syntax
------

ON COM GOSUB line number

Example
-------

::

   10 ON COM GOSUB 100
   20 COM ON
   100 'SUBROUTINE TO READ
   110 'INCOMING DATA
   190 RETURN

Remarks
-------

This statement is used in conjunction with the :doc:`com`
statement. It tells Basic where to jump to in the event of a
communications interrupt.

Data may be left in the communications buffer for as long as is
necessary.

On an interrupt an automatic ``COM STOP`` is executed so interrupts are
never nested. The :doc:`return` from the trap routine performs
an automatic ``COM ON``, so re-activating the interrupt routine, unless
a ``COM OFF`` statement was executed before the RETURN.