>> yesterday I found A/UX stuff in there
>> ftp://ftp.geo.tu-freiberg.de/pub/incoming/
>> [...] 
>> AUX_3.0.1_Install.toast_image.gz
>> AUX_3.0.1_Install_Boot_Disk.diskcopy_image.bin
>> AUX_3.1_Update.toast_image.gz
> 
> I downloaded these, made a floppy disk and a multisession CD-ROM from them and
> tried to boot my Quadra 840AV from that floppy.  The only thing I got was a
> dialog box reading "This startup disk will not work on this Macintosh model.
> Use the latest Installer to update this disk for this model.  (System 7.1 does
> not work an this model; you need a newer version that does.)"

First of all, you should be able to get the floppy to boot by adding the
proper system enabler for the 840AV. I think that there is one on the
floppy, but it is probably for something like the Q950.

> Is there a place out there where I could get a boot floppy with some newer
> system - 7.5.5 for example (can I just use the 7.5.5 installer to update
> mine?)?  Where could I look up which machine is able to run which MacOS and
> which A/UX version, if any?  Has somebody  got A/UX to run on a 840AV at all?

Now the bad news... IIRC, A/UX will not run on an AV Quadra as there are no
drivers for the special/different hardware. It will also not work on any LC
system and requires an FPU on supported systems.

Keeping this somewhat on topic...

I gather that 1.5.1 is broken on the AV Quadras (as well as possibly
some/all other 68k Macs). Is there a patch(s) which can be applied to a
kernel source tree, rather than staying at 1.5 or waiting for 1.5.2?

Thanks...
<<<john>>>