Re: Booting a 660AV?

[Mouse <mouse%Rodents-Montreal.ORG@localhost>]

>>>> But this machine's keyboard is ADB and video is a DA-15.
>>> Why 'but'?  It's a Mac.
>> "But" in the sense of "This is a problem, and here's why".
> Find a used one in a thrift store, or on your local equivalent of
> craigslist?

Possibly.  But see below.

> I could lend you one, but you are right in the middle between
> Frankfurt and Vancouver, and they don't let you open a window in
> planes.

And I doubt it would be much use after falling from that altitude
anyway. :-/  Unless you have access to stasis-field tech....

> (And don't get me started about Canada Post.)

I have had little trouble from Canada Post myself, but I have rarely
used it for anything but letters.

>>> (or get an ADB converter
>>> <https://www.bigmessowires.com/usb-wombat/>),
>> Love to, but they give no indication how to find a brick-&-mortar
>> near me which carries the silly things.
> It's actually a very nice gadget, [...]

I'm sure it is.

I wonder if there'd be enough customers to sustain a business whose
raison d'être is to be a brick-&-mortar for things that don't have one.

>> I think I may have an ADB keyboard somewhere; I certainly hope
>> so....
> So what was the complaint about, then?

Basically that it will be somewhere between "a significant level of
bother" and "have to acquire new(-to-me) hardware I have no other use
for" to make it work.  (And that's assuming the hardware is in working
shape at all, which remains to be determined.)

Not that that's valueless.  But when I'm in a period of trying to
divest myself of hardware, not acquire more, the effective cost of
doing such things rises significantly.

>> A Mac DA-15 to VGA adapter is entirely passive?  [...]
> This might help 
> <https://www.bigmessowires.com/2023/10/04/classic-macintosh-video-signals-demystified-designing-a-mac-to-vga-adapter-with-lm1881/>.

Oof!  There is clearly a lot more going on here than I'd realized.

I've dug into my video-adapters collection.  I found a DE15-to-DA15
adapter, obviously one I soldered up; looking at the wiring, it appears
to be designed as a Mac-to-VGA adapter, though its monitor sense pins
are wired up in a way that makes little sense based on the
bigmessowires piece.

I tried connecting the 600AV to a handy flatscreen with that adapter.
I then plugged in power (and nothing else) and pushed the power switch.

I had to hold the power switch in to keep the power-supply fan running.
But I got no video.  The monitor might not like the video signal, but I
didn't even get any indication that it realized anything was connected
(no "no signal" OSD, for example; it didn't wake up from its
pseudo-power-off state).

>>> And that hardware is very diverse, it was never meant to be a
>>> standard interface.
>> But no more difficult than what the NetBSD kernel already does
>> during autoconfig, surely?  Or does NetBSD/mac68k depend on some of
>> the hardware being set up already?
> The latter, especially for video card support.

I would be fine with giving up video support.  Provided it doesn't fry
anything, I'd be fine leaving the video hardware uninitialized and
using serial console.

But I'd expect the ROM code to initialize the video hardwqare enough to
not fry itself at least, in case there's no bootable OS accessible (eg,
no disk installed).

> Unlike for other architectures, there is no separation between
> firmware ("BIOS") and OS on 68k Macs.

Fair enough.  But that also means that NetSBD either knows how to drive
the hardware directly or is constantly calling into the ROM code to do
things.  Since IIRC 68k MACs tended to run without memory protection,
I'd guess the former is more likely.

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