INPUT$(nbr, [#]fnbr)
Will return a string composed of nbr characters read from a file or serial
communications port opened as fnbr. This function will return as many
characters as are in the file or receive buffer up to nbr. If there are no
characters available it will immediately return with an empty string.
#0 can be used which refers to the console's input buffer.
The # is optional. Also see the OPEN command.