Re: Developing PLATOTerm64, Flow Control woes.

From: Thom Cherryhomes <thom.cherryhomes_at_gmail.com>
Date: Tue, 3 Jul 2018 00:33:14 -0500
Message-ID: <CAPQyuQJ8KNz8BKuf_aGTW+gtDu_=tR41akss-D-8WTEeJQ=tWA@mail.gmail.com>
Wouldn't you know, extreme throttling of the connection with the following
chunk of code running as a proxy causes everything to come in. :)
https://gist.github.com/tschak909/a8e86e4fbed46eafac6350b17aecd2ea

Now it's me, in the lab fiddling with this until I can come up with
something that works with as little active involvement as possible. :)

Anybody with insights or wants to experiment, let me know, and I can get
you a D64 with the terminal and either a user account or use the guest
account. :)

-Thom



On Mon, Jul 2, 2018 at 12:52 PM Thom Cherryhomes <thom.cherryhomes@gmail.com>
wrote:

> The solution to me seems quite clear, I need to implement traffic shaping
> to throttle the connection down to something resembling modem speeds, while
> making a simple form of negotiation with my terminals to specify how much
> to throttle the connection.
>
> -Thom
>
> On Mon, Jul 2, 2018 at 12:49 PM Mike Stein <mhs.stein@gmail.com> wrote:
>
>> I'm a little confused and don't quite understand what you're saying:
>>
>> "The problem is large transmit fifo's "... "If you also have a large dumb
>> transmit fifo"..."
>>
>> Did you mean 'receive'?
>>
>> "This affects you whether you're using packets or an ascii terminal"
>>
>> Aren't we talking apples and oranges here? An ASCII terminal communicates
>> with whatever it's connected to, whether that's a packet 'modem' of some
>> kind, a 'normal' modem or a direct connection.
>>
>> The bottom line IMO is that if it's available then RTS handshaking is the
>> way to go; if not, and you can live with the 'no binary' restriction then
>> end-to-end XON/XOFF flow control can work just fine over the internet.
>>
>> With properly configured hard- and soft-ware, effective flow control is
>> quite possible. Most of these devices are intended to transparently replace
>> an RS-232 connection, so if it works over copper wire it should work just
>> as well over USB, Ethernet, WiFi, whatever.
>>
>> m
>>
>> ----- Original Message -----
>> From: "smf" <smf@null.net>
>> To: <cbm-hackers@musoftware.de>
>> Sent: Monday, July 02, 2018 4:10 AM
>> Subject: Re: Developing PLATOTerm64, Flow Control woes.
>>
>>
>> > On 01/07/2018 20:22, Mike Stein wrote:
>> >> Keep in mind that XON/XOFF expects a fairly immediate response; a
>> common issue using it these days is that you're not necessarily receiving
>> single characters but packets and you could receive quite a few characters
>> before XOFF has any effect.
>> >
>> > The problem is large transmit fifo's and the uart neither understands
>> > the concept of flow control, nor allows the driver to pause
>> > transmission. If you also have a large dumb transmit fifo, then it may
>> > be a while before you can tell the other end to stop sending (and if
>> the
>> > other end has sent an xoff then someone is going to be losing data).
>> > This affects you whether you're using packets or an ascii terminal.
>> >
>> > xon/xoff also shouldn't be used as an end to end flow control over a
>> > modem/the internet as the transmit fifos in those will certainly swamp
>> you.
>> >
>> > sending xoff as soon as you start receiving and only sending xon once
>> > all the data has been processed is as extreme as you can get, if that
>> > doesn't work then the problem you're trying to solve is actually
>> elsewhere.
>> >
>> >
>>
>>
Received on 2018-07-03 08:00:07

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