Re: Developing PLATOTerm64, Flow Control woes.

From: Thom Cherryhomes <thom.cherryhomes_at_gmail.com>
Date: Tue, 3 Jul 2018 01:21:14 -0500
Message-ID: <CAPQyuQKLOEFW9ysfR9T8sVJvGL0TZGxWdzKD9dhudKxvpaWsPA@mail.gmail.com>
from the user's perspective, I have. What else can I realistically do? If I
am having to work around the problem in modem firmware, I've lost.

and I am not able to alter very low level system code (which is written in
CDC assembler, do any of YOU know how to program a 60-bit control data
supercomputer?) ;) sooo

again.. if anyone has any better ideas, lay them on me.

-Thom

On Tue, Jul 3, 2018 at 1:05 AM David Roberts <daver21145@gmail.com> wrote:

> If you are throttling things, then presumably you haven't 'fixed' the
> problem - you have just made it less likely to occur...
>
> Dave
>
>
> On Tuesday, 3 July 2018, Thom Cherryhomes <thom.cherryhomes@gmail.com>
> wrote:
>
>> 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 09:00:25

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