[Coco] Fwd: IP packets on my coco

Brett Gordon beretta42 at gmail.com
Fri Jun 10 18:03:22 EDT 2016


The "soft" interrupts (aka polling) that nitros uses is indeed 60 hz.

Brett M Gordon
On Jun 10, 2016 4:52 PM, "Dave Philipsen" <dave at davebiz.com> wrote:

> So I have a question since it has been many years since I wrote an OS9
> device driver.  If the driver is written to poll the device instead of
> being interrupt driven, how often will it poll the device to check for the
> necessity to service it? Once each tick?
>
> Dave Philipsen
>
> > On Jun 10, 2016, at 1:38 PM, John W. Linville <linville at tuxdriver.com>
> wrote:
> >
> >> On Thu, Jun 09, 2016 at 09:47:56PM -0500, RETRO Innovations wrote:
> >> On 6/9/2016 9:35 PM, John W. Linville wrote:
> >>>> Well, it looks like the datasheet might be wrong...
> >>>>
> >>>> Application Note 181 from Cirrus Logic says:
> >>> https://www.cirrus.com/en/pubs/appNote/an181.pdf
> >> I was looking for that all day.  Glad you found it.
> >>>> So apparently the 8-bit mode is a bit unreliable in the CS8900A?
> >> No, it's rock solid on the CBM platform, so I expect it would be the
> same on
> >> the Coco.
> >
> > Except for the whole interrupts thing... ;-)
> >
> >>>> With that said, the usefulness of interrupts for servicing an Ethernet
> >>>> NIC on <2MHz CPU is debatable...
> >> Most folks appreciate the idea of getting an IRQ when a packet
> arrives.  In
> >> most newer switched Ethernet environments, you won't see any packets
> until
> >> one comes for you.  Thus, you can safely do other stuff and then an IRQ
> will
> >> mean there is actual data for you.
> >
> > Yeah, I understand the interrupt concept.  I know a fair amount about
> > switched Ethernet as well.
> >
> > Despite the convenience of asynchronous notifications, one must also
> > consider the relative costs of polling versus processing interrupts
> > and how often one expects to recieve incoming packets while an
> > application is running.  Moreover, I find that a number of otherwise
> > competent coders have trouble when dealing with interrupt-driven code.
> > So all-in-all, I still submit that not having an interrupt signal in
> > this case is not a big deal.
> >
> > Anyway, the Cirrus Logic chip vs. the Realtek chip is much ado about
> > nothing.  Either will do the job equally well or equally poorly,
> > depending on your point of view... :-)
> >
> > John
> > --
> > John W. Linville        Someday the world will need a hero, and you
> > linville at tuxdriver.com            might be all we have.  Be ready.
> >
> > --
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