Re: 4400/200: next issue!

[David Riley <fraveydank%gmail.com@localhost>]

On Sep 6, 2021, at 6:35 PM, Mouse <mouse%Rodents-Montreal.ORG@localhost> wrote:
> 
> Okay, thanks to everyone who helped, I have my 4400/200 powering up
> now.
> 
> Next problem: having trouble finding the relevant serial port - if
> there is such a thing.  I found references saying that for serial
> console I want the modem port, which is fine, BUT...
> 
> ...I can't seem to find the relevant pins.
> 
> The connector looks like the miniDIN-8 I'm used to from SPARCStations,
> only with a 9th pin.  I found a Sun cable that brought the 8 pins it
> supports out to a DB-25.  Pin 7 - the usual ground pin - shows a
> sub-1-ohm connection to circuit ground, so I figured I should be able
> to find the data pins by looking for pins driven by the machine.

Mac serial ports are decidedly different from Sun ones.  They're nominally RS-422, but they're mostly compatible with 232 with appropriate adaptors.  The most common ones you'll find are Mac->DB-25, since they were largely going to modems; not a lot of MiniDin-8->DE-9 ones out there, but usually a small set of adaptors will get you where you need to be.

Here's a useful primer (reasonably plain HTML, as compared to a lot of the ad-encumbered pinout sites out there these days): http://www.wam.umd.edu/~zben/mac/MacSerHard.html

> 
> I then tried the other port - the one marked with a printer icon
> instead of a phone handset icon - and got just as much nothing.

On a PowerPC, the printer port is going to be basically the same as the modem port (on 68k machines there were more significant differences, largely due to interrupt priority, but on PPC it's largely irrelevant; same 8530 hardware as Suns, though, not least because Apple used the SDLC modes of the 8530 for LocalTalk).  That said, it does matter as far as which one you're talking to, and I don't remember which one maps to the first tty.

> Of course, the dead battery means any settings will have been lost.
> Does this mean that I shouldn't expect anything on the serial ports
> upon powering up with neither keyboard nor monitor connected?

Correct.  OldWorld Macs talk OpenFirmware out the serial port by default, but only with a cmd-opt-OF startup key combo.

> I don't
> know where my ADB keyboards are, nor any Mac monitors (I used to have
> one, not sure whether I still do).  Is it possible to drive a VGA
> monitor off the Mac DA-15 video with a passive adapter?  If so, where
> would I find the pinouts?

Yes, they're actually reasonably easy to find, but I would strongly recommend the Griffin MacPnP adaptor, which allows better control of the monitor sense lines (newer PowerMacs should do fine with just the VGA DDCs, but some may have some weirdness with it and it's sometimes just easier to set the Apple sense code instead, which the MacPnP lets you do).  Let me know if you need one, I bought a few dozen a few years back when I came on a deal.

ADB is a bit of a tougher nut to crack; there aren't a lot of adaptors out there (though there are a number of open source projects), and ADB really isn't compatible with anything else, at least not directly.  I have a few spare Apple Design Keyboards and plenty of mice, though, and would be happy to part with a pair as well.  You do need it to get into OpenFirmware, one way or another.

> I could solder one up, and, even if it
> doesn't work perfectly, it might work well enough for me to change
> settings.
> 
> Of course, I'd then still need to find an ADB keyboard.  I'm pretty
> sure I still have one, just not sure where it might be.

Like I said, offer's open.  Free to a good home.


- Dave