[hylafax-devel] Re: Modem Reset Commands

[Nico Kadel-Garcia <raoul@adsl-151-203-22-73.bellatlantic.net>]

On 19 May 2000, Dmitry Bely wrote:

> Nico Kadel-Garcia <raoul@adsl-151-203-22-73.bellatlantic.net> writes:
> 
> > > Seems we have finally reached consensus :-) So you are agree now with
> > > explicit ModemSoftResetCmd (ATZ), issued *before* any other initialization
> > > activity? Who else is against it? :-)))
> > 
> > Works for me. Can we gracefully make it something like "ATZ\nAT&F" in order
> > to restore the modem to the factory default, or do we have a separate
> > AT&F slipped in elsewhere?
> 
> Personally I am against it. I like to store some site-specific values
> (e.g. TX level, required for the specific telco line) and don't write them
> to init strings of each and every application. Also take into account that
> Hylafax sets *all* parameters needed for correct faxing itself. Anyway, if 
> someone really needs AT&F, he/she can easily add it to ModemResetCmds
> string.

Sigh. That's the problem: you are storing non-modem specific information
and relying on it for every session, then you turn around and say
HylaFAX sets all the stuff needed for faxing.

HylaFAX also does data, and other modems can and do use the phone. If I
swap the modems from one system to another, it is *possible* for someone
else using it to have it in a really unfortunate state that will be
restored by ATZ and the power cycling.

> > My concern is the potential misconfiguration
> > by other applications, restored by an ATZ.
> 
> ATZ state is automatically restored
> a) after power-on
> b) after DTR drop
> 
> So if your (or someone's else) installation works now, it will also work
> after explicit ATZ in the beginning. Nothing will change. What should we
> test? (I also reply here to your parallel message)

You're clearly missing the point. Here's a potential timeline.

	I install and run HylaFAX on my brand new dual-boot
	Linux machine with Zoom modem. It runs, I'm happy, I work from a
	known good state

	I install SCO Xenix on another partition (yecchh!!!). Zoom
	sends me the ghods-awful init strings of death they used to
	send out, completely uselessly, and I try to get UUCP working.
	I store the configuration, which is just plain wrong for
	anything useful, and it never works correctly.

	I reboot to Linux, thankful to escape with my life, and
	ATZ is now restoring my modem to some state invented by
	the drunkard with a Ouija boards called "UNIX tech support"
	at Zoom. I am now dead in the water until I do an AT&F, possibly
	followed by an AT&W, to get ATZ working the way I expect again.

I believe that the behavior of ATZ is to some extent modifiable by the
registers. Working "on any reasonable installation" is not enough: most
sites don't folks as smart as us to go in and do this kind of resetting
by hand.

-- 

			Nico Kadel-Garcia
			nkadel@bellatlantic.net


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