Suppose you have a Fax-modem and you want to receive faxes late at night or during your absence. Up to now the only way to do this was to keep your Mac running at all times.
No longer.
PreFax is a piece of hardware that enables soft power on/off Macs to be turned on when the modem receives a telephone call (or fax call).
The Après Fax control panel takes care of shutting down your Mac depending on what caused it to start in the first place. If the Mac was woken by an incoming call (fax) then it is assumed that the only reason for running was to receive a fax. You can specify after what period of time the Mac should shut down after wake up in the Après Fax control panel. If it was not the phone that woke the Mac, then Après Fax won’t do anything.
Together PreFax and Après Fax can be used as an unattended fax answering machine, one that only runs when necessary.
Version 2.0 remedies two problems the original set had.
1. On newer Macs, (from the 630’s onwards and Macs running 7.5.1 and up) the power-on key on the
keyboard functions as an on/off switch. When the Mac is off when you press the key it will come to life,
if it runs it will ask you whether it should shut down. While in itself this is useful, it is quite annoying when
the Mac has a Prefax attached. PreFax has the same effect as pressing the PowerOn key on the keyboard, so
every time the phone rings while the Mac is on you will get the shut down dialog. This problem is now fixed
in hardware.
2. The boot process on Macs is rather slow. This is of course partially caused by the number of extensions/control
panels to be loaded and partly because the Mac is a slow starter. Often the Mac would be ready to receive a fax
just too late. Version 2.0 speeds up the boot process by telling an extension manager (not included) to only load
a certain set of extensions/control panels. This reduces the amount of time needed to get the Mac ready to receive
a fax.
Requirements
What you need for this scheme to work is:
• a Mac with soft power on/off (that is, a Mac that can be powered on by pressing the key marked [< ]
on the keyboard and that can be switched off by choosing shutdown in the special menu).
To date at least the following Macs have this feature (information taken from macfactstwo941002.txt):
- All Duo's when docked (mini or full dock, or floppy adapter, else there is no ADB port).
(Duo 210, 230, 250, 270c, 280, 280c)
• a modem that supplies a Ring Indicator signal (pin 22 on a DB-25 RS-232 connector).
Most modems equiped with a DB 25 connector do so.
For laymen: If your modem has a connector at the back and it has 25 pins (one row of 13 and one row of 12 pins)
then you are in luck. If your modem has a cable attached to it directly and this cable only has a connector with 8
(or 9) pins, then you should contact Ronald Leenes (address below) for another solution. Examples of modems
for which the PreFax described here does NOT work are the Global Village modems.
• Prefax II, the hardware described in this document (or alternatively, if you don't know what a soldering iron is,
or if you have money to spare instead of time, the one you can order at the address below).
• Après Fax 2.0, the control panel bundled with this document.
Theory of operation
When your modem is powered on it will signal the attached computer when it receives a telephone ring by means of a signal on the RS-232 port (the Ring Indicator line, pin 22).
Normally your Mac does not use this signal, since the Mac does not use all modem lines but just the bare minimum. Besides using this dedicated line, the modem also sends a verbose signal (the word “RING”) over the serial data line. Since normally your Mac will be running when you want to receive a fax, this verbose signal suffices. Therefore there is no need to use the ring indicator line in those circumstances.
If we want to use the Mac and Fax modem unattended the verbose signal will not suffice because the Mac won’t be running when the fax arrives, so it won’t be capable of reacting to the string “RING”.
This is where PreFax comes in.
PreFax is connected to the Ring Indicator line on your modem and to the PowerOn line on the ADB bus (pin 2) to which the keyboard and mouse are connected.
When you press the PowerOn key on the keyboard, the PowerOn line is pulled to ground. This signals the PowerOn circuitry in the Mac to start the computer.
PreFax does the same thing, it pulls the PowerOn line on the ADB port low when the ring indicator line on the modem RS-232 port becomes high.
So if your modem is powered, your PreFax will wake the Mac on the first ring it receives.
Complication
Now as stated in the introduction, the Newer Macs behave a bit differently with respect to starting up and shutting down. The new Macs, and Macs running System 7.5.1 and up, can also be shut down by pressing the Power key on the keyboard. Since this is what PreFax does, we have a problem. The Mac has no way of knowing if it was the user or Prefax that pressed the Power key. We need a trick.
The ADB also has a 5 volt line which is used to power keyboard and mouse. Since this line only supplies 5 volt when the Mac is actually running we can use this line as a detector for Prefax telling it when not to do its trick.
For a real fax machine we need some more.
Not only do we want the Mac to start up when a fax arrives, we also want it to shut down when the fax is received. For that purpose we made Après Fax. This control panel shuts down the Mac after a specified time. In this respect it resembles the numerous extensions that already exist (like AutoShutD, SDI etc). The difference with these other extensions/control panels is that Après Fax monitors the serial port to see if it was the modem that woke the Mac. When the Mac boots, Après Fax will ask the modem if there are phone rings coming in. If that’s the case (we do that by polling register 1 of the modem, the ring counter register), this tells Après Fax that it should signal an extension manager to only load the extensions in a set named F, and that furthermore it should shut down the Mac after a period you specify in the control panel (1, 5, 10, 15 or 30 minutes).
If the ring counter register of the modem is 0 on start up, we can assume that it was you that turned on the Mac. Après Fax won’t do anything.
Operation
Operation is fairly simple. Drop the Après Fax control panel in the extensions folder within your system folder,
yes that’s right in the extensions folder. This is to ensure that it loads before the control panels.
In your favorite extensions manager (we’ve tested Now StartUp Manager and Duo Extension Picker), create a set of extensions that you call F. This set obviously should only contain the necessary extensions/control panels needed to receive faxes.
Make sure that Après Fax loads directly before the extensions manager.
Open the control panel and specify the amount of time you want the Mac to run after startup.
Shut down the Mac. Install the PreFax DB-25 block between the modem and the modem cable.
Install the mini-Din 4 block between your Mac and the keyboard cable.
Presto. Now you're ready to run.
The ADB facing the back of the Mac!
Perfect?
Well there still is a problem. The Mac takes fairly long to boot, even with a few extensions. So the fax/fax-modem on the other side may have given up before your machine is ready to accept the incoming fax. Most people are sensible enough to try after a few minutes. If they don't ask them to do so.
Shopping list
PreFax is simple to build. All you need is:
• a DB-25 connector male
• a DB-25 connector female
• a mini-DIN 4 connector male (keyboard cable)
• a mini-DIN 4 chasis part (or mini-DIN 4 female, depending on how you want to construct your PreFax).
• two small signal transistors eg. BC 547
• one diode (1N4148)
• two 10K resistors
• one 100 Ω resistor
• some 2 cored wire (length depending on the distance your modem is away of the ADB port on the Mac).
Construction
Solder the DB-25 connectors back to back (pin 1-1, 2-2 , 25-25 etc). This leaves a compact block you can stick between the modem and the modem cable (like a gender changer).
Run a wire from pin 7 on either connector. This is signal ground. Run another wire from pin 22 of the DB-25's. This is the Ring Indicator line.
Solder the rest of the components as shown in the diagram. It does not make sense to construct a PCB for just 5 components. With a bit of folding all components fit in the casing of a mini-DIN 4 connector. The mini-DIN 4's can also be put back to back to form a small clump which can be fitted in the ADB port on the Mac (see photo). Before constructing the mini-DIN 4 block, look carefully at the back of your Mac to see how much room you have. Some Macs have little room below the jack.
Legalese
Après Fax is shareware. You are encouraged to spread this control panel provided this document is included.
If you use the control panel and build PreFax yourself, the shareware fee is $10.
You can send the the shareware fee in US dollars (or an equal amount in one of the currencies specified on the registration form) to the address below. The shareware fee includes updates on the Après Fax control panel and information on future products if you supply an e-mail address.
Not to do it yourself
If you don't want to build PreFax yourself, you can order one at the address below. The price of a built PreFax, including the Après Fax control panel, shipping and handling and the shareware fee is $40. Please allow for two to three weeks for delivery.
Please pay the shareware fee if you use this software and hardware. It will keep us developing useful software and hardware to enhance your Mac.
(including postage and handling) at $ 40 each ......
total: ......
Payment
Europe You can send cash (US Dollars or Dutch Guilders) or an EuroCheque. The Eurocheque must be payable in Dutch Guilders (DFL) and the cardnumber must be on the back of the check. People in the Netherlands can also tranfer ƒ65,- (inclusief BTW) to giro 1501465 t.a.v. R.E. Leenes, Zutphen.
Outside Europe You can send cash (US Dollars or Dutch Guilders) or an International Money Order. Do not send local Money Orders of foreign drafts (e.g. U.S. Money order or Canadian Money Order). An International Money Order has “international money order” written on it.
Do not forget to send in the registration form as well!
