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PowerBook Duo Wifi Modem


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@Trash80toHP_Mini Very interesting, thanks for posting! Just the DAA then. So using a dock's "modem" must seemingly require the internal modem? That would explain why there's a line in the above diagram going from the MUX to the expansion connector.

 

1 hour ago, Challenger 1983 said:

What would be the equivalent of the rockwell chip on this board?

 

@Challenger 1983 I believe the answer is that there isn't an equivalent. The pictured boards seemingly just contain the Digital Access Arrangement circuitry (step down x-former, signal conditioning, surge suppression, etc.).

Given that, the two biggest outstanding question I have are:

  1.  Whether modem communication is possible when docked via one of those modules pictured above, but without an internal modem? For instance, the crummy soft modems (often called winmodems) of the day were just DAAs with some port interface requiring the CPU and installed software to emulate the hardware.  Does the Duo potentially implement something similar?
  2.  Did Apple provide some sort of non-ASIC (Rockwell or otherwise) equipped basic module in place of the modem version with just power/reset buttons if a Duo was ordered without the internal modem? I've never seen such an animal, nor have I ever seen a Duo without an internal modem, but my experience with this platform is pretty limited. This passage is lifted directly from the Duo "Getting Started" manual, which strongly suggests that not all Duos shipped with internal modems: "Apple offers an optional, low-power, internal fax/data modem for your computer."
Edited by sutekh
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54 minutes ago, sutekh said:

@Trash80toHP_Mini Very interesting, thanks for posting! Just the DAA then. So using a dock's "modem" must seemingly require the internal modem? That would explain why there's a line in the above diagram going from the MUX to the expansion connector.

 

 

@Challenger 1983 I believe the answer is that there isn't an equivalent. The pictured boards seemingly just contain the Digital Access Arrangement circuitry (step down x-former, signal conditioning, surge suppression, etc.).

Given that, the two biggest outstanding question I have are:

  1.  Whether modem communication is possible when docked via one of those modules pictured above, but without an internal modem? For instance, the crummy soft modems (often called winmodems) of the day were just DAAs with some port interface requiring the CPU and installed software to emulate the hardware.  Does the Duo potentially implement something similar?
  2.  Did Apple provide some sort of non-ASIC (Rockwell or otherwise) equipped basic module in place of the modem version with just power/reset buttons if a Duo was ordered without the internal modem? I've never seen such an animal, nor have I ever seen a Duo without an internal modem, but my experience with this platform is pretty limited. This passage is lifted directly from the Duo "Getting Started" manual, which strongly suggests that not all Duos shipped with internal modems: "Apple offers an optional, low-power, internal fax/data modem for your computer."

So essentially the Modem board just handles the step down and conversion from 48vAC, I’ll look through the developer notes some more and see if i can find an answer as to how the modem is operated when the Duo is docked.

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I thought you guys'd get a kick out of that pic.

 

I'm guessing the Modem uses the (missing) serial port of the 2300c and that it probably ties up the Modem port of the DuoDock and MiniDock, though I don't know from experience.*** That'd be the way things worked in the Performa era, Apple plugged up the Modem port connector on models with a ComSlot Modem. Who knows? The Dock and MiniDock are multi-function PDS expansion cards at Slot $E IIRC. Anything could go in such a setup, much did.

 

As I'd said, these are the only Modem specific lines I found on the Docking Connector:

 

143____ DAA CNTLF___Modem DAA control
144____ DAA ID IN_____ID input from 152-pin connector to Modem card
145____ /RING DET____Ring detect signal from the modem DAA
146____/RB DVR_______Modem relay B driver
147____/RA DVR_______Modem relay A driver

 

Are th0se enough to connect between the Duo's "Internal Modem" and the Dock/DAA board? Ports-n-Pinouts has these Duos labeled Modem or Printer, on the 2300c it's Serial Port.

 

Duo-n-Dock-ports.JPG.7ba263e63842e3cc12d55d05bd40f5de.JPG

 

*** I had a much faster portable external in my bag that had all the PowerBook specific bits I needed when the same package came out in a faster version for PC. Beautiful little Charcoal things. I only ever really used the internal Modem to FAX AI layouts out on one of a customer's lines back to myself on the LaserPrinter FAX machine line in his office for markup, then edit and back around again. Took about 35 iterations to finalize THE most notoriously confusing Parking Lot Rate Sign in the Big Apple. The Times made it a poster girl, but she was well within the letter of the law, they should have printed a picture of one that broke one. [:D]

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I had a bit of a eureka moment on this topic yesterday. I stumbled across a more generalized "Macintosh Duo System" Developer Note that I hadn't encountered before on other sites:

Remarkably, chapter 5, Internal Modem, includes nearly all of the detail so glaringly absent from the 280c's specific Note and answers many of the questions posed above. Here are a few highlights:
 

  • As theorized, the internal modem including the Rockwell "data pump" is absolutely required for docked modem communications. Duo Dock and MiniDock only provide the DAA via the pins on the 152-pin connector you've identified above @Trash80toHP_Mini (see Fig. 5-6 & 5-7)
     
  • Per the following, it sounds like there is indeed a software abstraction layer included in the Express Modem driver which is what I suspect I was interfacing with above:
    • Many of the modem and fax functions are implemented in software running on the PowerBook Duo’s operating system. This allows easy field upgrades, and reduces hardware costs. This type of architecture also makes it easier to add new features to the modem.
       
  • There's a partial pinout of the modem's 50-pin connector beginning on pg.58. Unfortunately it only seems to cover power and analog signaling :/ What the other 25 pins do remains a mystery...
     

So here's where I think that leaves me: Working with or bypassing the Express Modem software layer and split-serial architecture isn't in my wheelhouse. But, I have a glimmer of hope... The 280c's Developer Note includes the following two passages:
 

  • When describing the GetIntModemInfo routine on pg.58, the following condition is included: "Modem is a serial modem" among other options pertaining to Express modem installation
  • Pg.29 includes the following: "If you have a third-party internal modem installed, the control titles will be Internal Modem and External Modem"
     

Whether on not a 3rd party serial modem was ever offered for the Duo platform, I can't say (there's certainly no hint of it on today's internet), but it seems clear to me that Apple at least included hardware and software provisions for such a device. I wouldn't be at all surprised if one or more of those undocumented pins on the 50-pin header included a modem ID pin signalling the software how to behave. E.g., Pin X grounded, Express modem installed, software modem emulation enabled, CTB and PB Setup CDEV options updated accordingly. Pin Y grounded, serial modem installed, PB Setup CDEV options default to traditional Internal / External options. That's how the PB 1xx does it FWIW (pin 15 to GND = modem inserted, pin 16 low = serial modem).

I'm not about to start randomly grounding pins, but neither have I given up hope that there's a way to make this work...

 

Edited by sutekh
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