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Modem init strings are commands that your modem software (e.g.
Telix) automatically sends to your modem when the program first
starts. They are roughly the equivalent of a morning cup of
coffee for your modem. They wake it up and get it functioning
normally. Without them, your modem will do all sorts of dim-
witted things.
A modem learns how to behave from three sources:
1. DIP switch settings on the back, front or inside the
modem. Regrettably, the trend is to have no switches.
2. EAROM. Electrically Alterable Read Only Memory. You
send a modem a set of commands, then send it a special
traumatic Write command (usually &W) that causes it to
remember that particular configuration forever. Ever
after, when the modem powers on it automatically goes
into that remembered mind-set. This approach is
dangerous. You can, for example, accidentally burn
into the modem's little mind that it should never again
pay any attention to any further commands.
For further reading, try Arthur C. Clarke's novel (the
name of which temporarily escapes me) where the lead
character experienced the equivalent of at &W command
while having sex with a honey-flavoured girl named
Kalindy.
3. Modem Init strings. Each time you run your modem
program, it sends your modem a series of commands to
set it up the way you like. This is the most flexible
approach, since two different programs can then easily
set up the same modem in two different ways. Whenever
you power the modem off, it forgets everything it
learned from the modem init strings. This amnesia
feature is both a blessing and a curse.
In practice, you may use a combination of all three methods.
DIP SWITCHES
Modems often have a set of eight DIP switches for configuring.
They usually look like this:
- - _ _ _ - - _
1 2 3 4 5 6 7 8
1. Should be UP so that DTR (Data Terminal Ready) is
obeyed. Otherwise the modem ignores the computer when
it lowers DTR to request a hang up. This can later be
overridden with the &D2 command.
2. Should be UP to request verbal result codes such as
CONNECT or BUSY rather than incomprehensible numeric
codes. This can later be overridden with the V1
command.
3. Should be DOWN so that the modem presents result codes
to the commands it receives. If it were UP, the modem
would play dumb and give no responses whatever. This
can later be overridden with the Q0 command.
4. Should be DOWN so that the modem does not echo commands
back to the computer. If it were UP, the modem would
back-talk every command the computer gives it along
with the result of the command. This can later be
overridden with the E0 command. Some software may
require this switch to be UP.
5. Should be DOWN to suppress auto answer. THIS IS VERY
IMPORTANT. Even if you send a modem init string
containing S0=0 to suppress auto answer, your modem
will still answer the phone during the interval between
when it is first powered on and when you first run your
modem software.
6. Should be UP to have normal DCD -- Data Carrier Detect.
Otherwise your modem will lie to your computer that the
other modem is still attached and working even when it
has hung up. This can later be overridden with the &C1
command.
7. This should usually be UP for normal single-line
phones. It should be DOWN for multi-line phones. You
can later override this with the &J0 command.
8. This should be DOWN to enable the modem's intelligence.
If it were UP, the modem would totally ignore all the
commands you send it -- emulating an old-fashioned dumb
modem.
Please read your modem documentation to find the true meaning of
the DIP switches. The documentation that comes with your modem
will not necessarily match the explanations I have given above.
Believe it, not me! If you did not understand the explanations
above, not to worry, just be patient. It should come clear when
you read the my expositions on the related commands.
HOW DO YOU GET MODEM INIT STRINGS INTO YOUR MODEM?
If you have Telix, optionally type Alt-Z for a menu, type Alt-O
to change the cOnfiguration, then select M for Modem and dialing,
then select A to change the modem init string, then type the
string followed by Enter, then hit Esc, then select W to write
the configuration to disk making the changes permanent.
Ever after, Telix will remember your init string. It will
automatically send it to your modem every time it starts.
This page created by ng2html v1.05, the Norton guide to HTML conversion utility.
Written by Dave Pearson