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'This example uses the OPEN COM statement to open the COM1 port for input
'and the COM statement to enable event trapping.  The ON COM statement
'passes control to a subroutine when there is activity on a terminal.
 
'Note: To run this program, you must have a terminal connected to
'the COM1 port.
 
CLS
'Set up error handling in case COM1 doesn't exist.
ON ERROR GOTO ErrHandler
'Open the COM port.
OPEN "COM1:9600,N,8,1,BIN" FOR INPUT AS #1
 
'Turn on COM event processing.
COM(1) ON
'Set up COM event handling.
ON COM(1) GOSUB Com1Handler
'Wait for a COM event to occur or a key to be pressed.
DO
LOOP WHILE INKEY$ = ""
'Turn off COM event handling.
COM(1) OFF
CLS
END
 
Com1Handler:
    PRINT A$; "Something was typed on the terminal attached to COM1."
    RETURN
 
ErrHandler:
    SELECT CASE ERR
        CASE 68: PRINT "COM1 is unavailable on this computer.": END
        CASE ELSE: END
    END SELECT