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Re: LocalTalk support?



On   8 May, this message from Craig S. Cottingham echoed through cyberspace:
> On 2001-05-08 9:15, Michael Schmitz at
> schmitz@mail.biophys.uni-duesseldorf.de wrote:
> 
>>> i think the `nobody has bothered' is probably the explanation.
>> 
>> Nope, it's actuakky pretty difficult to implement and probably
>> not worth the hassle (at least not for anyone who'll never use
>> that feature, sorry this is how free software works).
> 
> No, I know. I'm half inclined to tackle this myself, but I'm
> currently too interested in spending time at my day job and with my
> family. :-)

May I suggest that indeed you spend the time with your family? I think
it's better used that way than writing a localtalk driver ;-). But if
you wanted to get a divorce, I could dig up some documents from Zilog,
the maker of the 8530 SCC serial chips, about how to implement
Localtalk.

>> Localtalk over
>> serial requires synchronous mode operation of the SCC and the
>> protocol timing constraints are pretty tight. You don't want to do
>> that sort of stuff in non-realtime context. In a multitasking OS
>> you don't want to do it busy-waiting in the interrupt handler
>> either. But you may see things different, please go ahead and prove
>> me wrong.
> 
> I used to write device drivers for DOS and Windows (years ago!), so I
> understand what you're saying. Ugh.

If you absolutely wanted to, you could always try to implement it under
some RT-extended Linux....

>> PC localtalk cards have a coprocessor to offload the protocol
>> handling to IIRC.

Correct, and two makes of cards are suported under Linux. No idea
whether they are PCI or ISA, though....

> Ah. I had an inkling this might be the case.
> 
> More and more, I'm thinking I just need to go ahead and buy that
> Postscript-capable laser printer I've had my eye on....

This is probably the best idea for b/w print. If you have
serial-port-equipped Mac running MacOS permanently, you could always use
that as a Localtealk-Ethertalk bridge (with Apple's software bridge).

Cheers

Michel

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