[Info-vax] modems and cxy08

[JF Mezei]

starchild wrote:
> This seems like it should be simple, but as always problems
> I have a VAX 4000-500 VMS 7.3 with a cxy08 with ckermit 8.0.201.
> I have connected to the cxy08 the bc19n-12 cable which is connected to
> 2 multitech modems.


SHOULD be simple, yes. But never is.

The original modems were simple. But when they cane out with fancy
features, compression and the like, they became more complicated.

Do you still have the manuals for your multitech modems ? You will need
to set them up to match the settings of your TX ports on your vax.

If VMS doesn't get the right control signals, it will hangup your modem
after 30 seconds. Or it will issue a message on OPCOM indicating your
modem is not wired properly.

Not sure where it is now, but in the "real" VMS documentation, there was
the IO Users Manual, and in it, there was a whole section on the
terminal driver which described in detail the logic involved with the
modem signals.

And the trick to test the modem is to dialup at 1200 baud when you modem
is physically connected at 19200 or higher. Then, you type a long file.
This will force the modem to do the flow control with the VAX because
the VAX will be feeding the modem at a much faster speed than the modem
can feed the telephone line.

I could try to resurect one modem and dump its config if you like.