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Re: OldWorld floppy and serial port work
Actually, my bad... turns out it was the other end of the serial line that's
the problem. :-) If I just use a Mini-DIN8->DB9 conversion and run it to a
*real* serial port on my Windows machine, it behaves; the Keyspan adaptor must
be having issues (it's been otherwise well-behaved so far, though). I just
took the macppc FAQ about the serial ports at its word, and I suppose that's
what I get. We might want to update that sometime?
Back to floppy-world... :-)
On Jul 8, 2010, at 3:46 PM, Michael wrote:
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> On Jul 8, 2010, at 12:46 PM, David Riley wrote:
>> Well, that's the problem; I have a 9600, which is probably somewhat
>> different than the serial port on the G4 (which is built in, but not exposed
>> by default, and I wonder if it's different hardware). All the way back to
>> the original Mac, they've used a Z8530 (just like Sun and everyone else who
>> wanted a *real* serial chip), and mac68k works fine. For me, if I look at a
>> man page, it stops responding to serial commands (though it'll still output
>> log messages, which is puzzling). The system log doesn't output any debug
>> info, so I'll probably have to start from the top.
> I would suspect interrupt problems. The G4 has a completely different
> interrupt controller ( OpenPIC instead of Apple's own ) which should not lose
> interrupts but Apple's might. If we enable an interrupt line that's already
> asserted it will not cause an interrupt for example. There is code in place
> to check this condition, it works fine with other devices but occasionally
> weird things happen - for example I get lost interrupt messages from the IDE
> chip on my beige G3 on first access to the disk with no further ill effects.
> And this does not happen with any other Apple IDE chip so it's probably a
> Heathrow thing.
> So, first thing I'd do is to run systat 1 vmstat and check if the serial
> port's interrupts still fire when thinks lock up and you keep sending. Since
> it happens on a G4 as well it's very likely not the actual interrupt
> dispatching code but something in the macppc-specific portion of the zs
> driver. In other words, what Donald Lee said.
> have fun
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