

Are the boards at all intelligent?  (I.e., run by microcontrollers?)  The
easiest thing would be to have another line that says that one of the
boards is talking to the PC.  When this line was true, the other boards
could all hold off and not send their data.  This isn't a perfect solution,
though, since you have to worry a little about making sure two boards don't
decide to talk at the _exact same time_.

Other than that, I think you will need to hook up each board to "something"
that speaks RS-232.  This actually isn't as hard (or as expensive!) as it
used to be, though.  Assuming the boards talk relatively slowly (9600 BPS
or slower), the PICs can coordinate things between themselves to multiplex
the data.  (This is really just forbicly adding the suggestion in the first
paragraph to your system.  And it assumes that each board doesn't talk more
than 1/8th of the time, of for very long, since a PIC isn't going to be
able to buffer more than, maybe 20-some bytes!)

You might want to check into the prices of multi-serial card for your PC,
though.  I recently bought a Boca Research 2x4 card (2 parallel ports, 4
RS-232 ports) for a very reasonable $85.