From: rfall@mv.us.adobe.com (Richard Fall)
Subject: Re: Have Suprafaxmodem wake-up when called?
Followup-To: comp.sys.mac.comm
Organization: Adobe
Date: Tue, 1 Sep 1992 06:18:26 GMT

In article <BtvK0t.AJn@iat.holonet.net>, kellys@orac.holonet.net (Kelly
Schwarzhoff) wrote:
> 
> I know that with the Powerbooks, one can turn them off and have them automatically
> "wake-up" when a fax is sent to them.  Question:  is there any way to do this
> with a SupraFaxmodem (using the FaxSTF software) on a Mac II?

I don't know the details of the SupraFax, but any modem that provides a
Ring
Indicator (RI) output can be made to turn on any Mac that supports the
Apple
Desktop Bus (ADB) power-on circuit.  Macs later than, I believe, the Plus
have this.

The method is relatively simple:  with two resistors and a transistor you
create a "switch" that connects the ABD power-on pin to ground whenever the
modem detects a ring on the incoming line.  These three parts are necessary
since the RI output from the modem swings between the RS-232 levels (-5 to
-12
volts to +5 to +12 volts, approximately), and the ADB power-on circuit is
looking for a contact closure to ground.

The downsides to this method:

    (1) The modem must be left on all the time, in order to
        provide the RI signal,

    (2) Since there is no "sleep" mode for non-Powerbook Macs,
        and since most fax machines give up and assume no
        answer after a few rings, the Mac must be set to
        boot up rather quickly.  That is, it must have very
        few inits, cdevs, and the like.

Otherwise, this method works rather well.  I use it at home on my Mac IIx,
in order to receive faxes with my DoveFax+ (external--the NuBus DoveFax
has the ABD power-on connection built in, I think).  Since the DoveFax+
doesn't have RI, I leave my Telebit WorldBlazer, which is on the same
line, powered on to provide the RI "wakeup".

In order to shorten the normally long boot time (it takes about 2
minutes to boot my Mac, since I have far too many inits and cdevs),
I have a suitably configured "quick boot" system, which I switch to
before leaving home using one of the freeware "System blessers".
There are probably other ways of doing this, but the idea is to keep
the boot time _very short_.  My Mac at home boots and answers the
phone by the sixth ring.

The "switch" circuit from the modem to the Mac ADB is rather simple:


RI ---+
      |
      R              -------- ADB
      1             /
      |           |/
      +-----------|   Q1
      |           |\
      R             \
      2              |
      |              |
      |              |
    -----          -----
    / / /          / / /
    
    
    R1, R2 = 10K, 1/8 w
    Q1     = 2N2222A


where RI is the Ring Indicator from the modem, and ABD is the ADB power-on
connection to the Mac.  The resistor values are not ?, and probably any
general purpose NPN silicon transistor can be used.

(NB--Although the circuit design is sound, and I have used this on my
     own machine, I accept no responsibility for any damage done to your
     equipment from use of this circuit.  Undertake this work only if
     you understand what you're doing and, as always--caveat emptor.)

You will also, of course, need to set up the Mac to fire up the fax or
other application once it's completed the booting process.

As I say, I've used this scheme for the last several months on my Mac,
and I've been able to receive every fax sent my way without having to
leave the machine on all day.

Have fun....

 +--------------------------------+-----------------------------------+
 |  Richard Fall                  |  Voice:  (415) 962-4889           |
 |  Adobe Systems, Incorporated   |  Fax  :  (415) 903-9652           |
 |  P.O. Box 7900                 |-----------------------------------|
 |  1585 Charleston Road          |  Internet:  rfall@mv.us.adobe.com |
 |  Mountain View, CA  94039-7900 |  UUCP:    ..!decwrl!adobe!rfall   |
 +--------------------------------+-----------------------------------+


P.S.--Do any of you Mac gurus out there understand enough of the Mac
      bootup process to know whether there's an easy way to have the
      Mac determine, _before_ the System has been booted, which
      System Folder is to be used, based on some external signal?
      I'd like to avoid the need, described above, for me to set the
      blessed System Folder before leaving the machine set up for
      fax receipt, and to have to boot the machine twice in the
      evening for regular use--once to bring it up under the "quick
      boot" system and change the blessed System Folder, then again
      to bring up the normal system.