GS Appletalk troubles

["John E. Townsend" <utownje@lexis-nexis.com>]

I'm trying to set up my IIgs to do Appletalk once again, and am about at
my wit's end (which, some would say, is not very far) trying to get it
to work.  The symptoms are pretty strange, and I'm starting to suspect a
motherboard hardware problem, but I thought I'd run it by here and see
if anyone has any other suggestions.  Here's the configuration:

   * ROM 3 IIgs with 8M RAM (7M CV RAM card in MEM slot). Self-test is
     OK.
   * RamFAST rev D 3.01e ROM with 1M cache in slot 7
   * SuperDrive 3.5" disk controller (with two FDHD drives) in slot 5
   * Clean startup disk with nothing but GS/OS 6.0.1 and the RamFAST
     driver

What happens is that the system pretty much hangs when I boot GS/OS:
the red progress meter marches all the way to the right, but absolutely
nothing happens (and no Init icons appear at the bottom).  If I press a
key and watch the text screen of the various modules loading, it stops
at the ProDOS FST without indicating any errors.  This only happens if
slot 1 or 2 is configured for Appletalk *and* a connector is plugged
into the corresponding port.  Here's what else I've figured out:

   * The ports work just fine for direct connections to a modem or
     printer.
   * The behavior is the same regardless of whether I'm trying to use
     the modem port or printer port for Appletalk.
   * Get this:  with slot 1 or 2 set for Appletalk, if I just remove the
     Localtalk connector from the corresponding port, GS/OS will boot up
     perfectly but (obviously) I can't access anything on the network.
     I know the Localtalk connector is OK because it works fine on my
     Mac SE/30.  I've tried other connectors too, and even tried them
     without any cables attached to them, with the same results.
   * ProDOS 8 applications will boot OK, even with a port configured for
     Appletalk and a connector plugged in, although I haven't actually
     been able to use the Appletalk connection.
   * If I turn off Appletalk on both slots, even with the connector
     plugged in, GS/OS will boot up OK except for the warnings about
     Appletalk being disabled.

Anybody have any ideas?  I'm all out, except for trading in the
motherboard.  Thanks!

--
John E. Townsend
Sr. Software Engineer          "Machines should work;
LEXIS-NEXIS                     people should think."
Dayton, OH, USA                        -- IBM Polyanna Principle
utownje@lexis-nexis.com