[Coco] Fwd: IP packets on my coco

Dave Philipsen dave at davebiz.com
Fri Jun 10 16:52:38 EDT 2016

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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