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Re: Serial Ports.



In article <31804D5A.42CB@tribeca.ios.com>,
Albert Hartman  <compexpr@tribeca.ios.com> wrote:
>Peter Schepers wrote:
>> 
>> In article <ufd94zbjse.fsf@ftp.ardi.com>,
>> Clifford T. Matthews  <ctm@ardi.com> wrote:
>> >>>>>> "Matthew" == Matthew Ballard <mballard@lausd.k12.ca.us> writes:
>> >In article <1.5.4.32.19960418021002.0066ea08@lausd.k12.ca.us> Matthew Ballard <mballard@lausd.k12.ca.us> writes:
>> >
>> >
>> >    Matthew> When Executor supports serial ports, will it also support
>> >    Matthew> AppleTalk via a port on my computer, because it would be
>> >    Matthew> useful access the AppleTalk networks at my school.
>> >    Matthew> Thanks, Matthew
>> >
>> >Probably not.  Most likely we'll support AppleTalk over ethernet, instead.
>> 
>> How can someone even start to support a protocol, which runs at ~230
>> kilobaud through unbuffered 8250's (16540's) that run at max. 115
>> kilobaud? Besides the baud difference, unbuffered UART's would likely be
>> losing characters at an astronomical rate (as is evidenced by
>> multi-tasking OS's like OS/2 which need at least a buffered UART just to
>> do 9600 without bit loss.
>> 
>> However, supporting appletalk over an ethernet card (ethertalk?) would
>> also seem to be very limiting because of the cost for individual users.
>> How could you hook up your PC to a standard appletalk laser printer using
>> an ethernet card, while not incurring much more expense?
>
>Well, I have a bunch of Tops Local Talk adapters for the PC. Also, Shreve 
>Systems, Sun Remarketing and a few other companies still have a supply of 
>PC Appletalk cards for around $29.00. IF the cards are available in 
>enough numbers, perhaps ARDI might support them further down the line.
>
>But, truthfully... Ethertalk is where the Mac is going. I probably does 
>make more sense to buy an AppleTalk to EtherTalk router for an older 
>network rather than dumbing down the PC to be compatible.

As the person who started part of this debate, I feel it necessary to add 
a few more things to the pot...

Most of the original postings asked about support for "appletalk over
serial ports". I don't recall any replies from ARDI which stated this was
*not* going to be done. 

Back in the old days of Apple, the protocol and cabling were both called 
Appletalk. This was later changed to Localtalk cabling, but the protocol 
was still referred to as Appletalk. Running this over ethernet was still 
only a gleam in someone's eye.

Nowadays we have appletalk over ethernet, but this is commonly referred 
to as "ethertalk", not appletalk. This is where much confusion seems to 
be creeping in.

When I originally posed my question about "how to support appletalk over 
*serial ports*", I never actually got any replies stating "this can't be 
done, and of course it won't be supported", which is what I still 
contend, but instead got a bunch of people telling me about the various 
Appletalk cards which use to be available (I know of these), and that it 
wouldn't be worth supporting this anyways, so we might as well go to 
ethernet.

Supporting only appletalk over ethernet (ethertalk) would seem to be a
very market-limiting strategy, since my interest in Executor would be to
be able to use it from my *home* pc, printing to my Laser Plus. No
ethernet capabilities here, along with a huge chunk of the already present
installed base of apple (and other manufacturers) printers. However, I 
don't think ADRI will have too many choices given the limitations of PC 
hardware.

I guess the point I am saying is I would like ARDI to make it clear what 
they are going to support. Saying they will support Appletalk isn't 
enough... they must specify the transmission medium as well. So if it 
will be "appletalk over ethernet" only, they should say "we will support 
ethertalk, using appropriate ethernet cards". Just saying appletalk is 
much too fuzzy, as it embraces both a protocol and a cabling system.

There, clear as mud now!

-----------------------------------------------------------------------------
 Peter Schepers,                 | 
 Dept. of Computing Services,    |   The opinions expressed in the above
 University of Waterloo,         |   rant are those of the poster, and not
 Waterloo, Ontario, Canada.      |   necessarily shared by anybody else on
 1-519-885-1211 ext 2456         |   this planet (or employer).


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