Wow, ok, I hadn't considered that someone had replaced the main rom.
All bets are off in that case.
I would not be surprised if the modem doesn't work at all with the wrong
rom installed. The main rom has to match the hardware and the North
American main rom does not match the European hardware, and the modem is
definitely one of the things, like the keyboard, which is different
between countries.
You only do something hacky like that fully accepting that you are
breaking some things in order to get some other things. But you didn't
make that choice, you're stuck with something someone else did and then
sold to you.
I would definitely start with putting the unit back to stock condition,
meaning put an EU main rom back in and remove the rex#, just as a first
diagnostic step just to establish a baseline even if you want to go back
to the hacked-up condition later.
Did the seller at least supply the original rom with the unit? If not,
it might be taped inside.
I don't know of any copies of the EU rom for download. Asking here or on
two facebook groups is probably your best chance to find one.
https://www.facebook.com/groups/Model.T.Computers
This one in particular has a lot fewer, but mostly European members:
https://www.facebook.com/groups/olivettim10
I think it can be dumped out the serial port with a BASIC program, so
anyone should be able to dump it for you without having to desolder the
chip or use an eprom burner. I'll try to find the basic program for
dumping the rom out the serial port, that way you can make it as easy as
possible for someone to do the favor by having some directions ready to go.
If the REX# really is incompatible with the EU main rom, and Steve can't
produce an EU version of the REX# firmware, then you'll probably just
have to choose one or the other for that unit, either have the hardware
all work properly, or have REX# on that unit.
--
bkw
On 2/3/22 17:40, Cedric Amand wrote:
Thanks, i'll try all that.
I must admit I don't fully understand what the REX# does, as I've only
use it to make backups of the RAM, but it's features go way beyond that,
so it's unclear to me if - for example - the tsdos that comes with would
be "US minded".
From what I understand, the original owner (which may even be in this
list) had to replace the belgian/european ROM with another ROM, most
likely a US one, to be able to use the REX# ( that's what I got from
what he told me, don't quote me on this )
All these changes could, maybe, break my modem.
However i've been looking at the schematics of the modem part and all of
this is as simple as can be, it's really purely analog in many areas,
and there is no way on earth any of this is software controller. I mean
: the thing doesn't care if the dial tone is 440, 600 Hz or anything (at
least looking at the hardware I see no way this would be measured, even
less handled by software)
So if I take for granted my M102 is a Belgian.european one (it' has the
sticker of the telco!), I guess the electronics where adapted to our
particular voltages.
What could be a possibility if that some of these are now out of spec
One final comment ; if I hit F4 (TERM) in TELCOM, the M102 starts to
emit an awful noise (like if it was connected to a data line !) it does
that even when the M102 is not connected to anything ( I mean, no wire
connected to it at all) It is also, afaics, completely crashed (i have
to reset/reboot)
Is that "normal" ?
That would point to a problem with ROM/REX...
thanks again for taking the time to help weirdo that wants his analog
modem to work :)
Le jeu. 3 févr. 2022 à 23:32, Brian K. White <b.kenyo...@gmail.com
<mailto:b.kenyo...@gmail.com>> a écrit :
I can tell you one thing for sure, the REX has no effect on the modem.
But you can prove that to yourself by just removing it. It doesn't hurt
anything and it won't even lose it's programming. Just pop it out, and
see that it made no difference.
Have you tested the line with a plain analog telephone?
Have you verified the modem cable doesn't have a broken wire?
Since you are talking about dialing vs answering, is the the ANS-ORIG
switch in the ORIG position? (Answer vs Originate)
Measure the voltage between tip & ring when the the modem is
on-hook. It
should be 48vdc
Measure the current on either tip or ring when the modem is
off-hook. It
should be about 20ma, at around 9vdc (actually a wide range from 3
to 12)
--
bkw
