[Coco] multiplexed serial into ip

[Boisy Pitre]

Gentlemen,

DriveWire 3 opens up the bit banger routines under NitrOS-9 for just  
what you want to do.  The DW3 subroutine module has 6 entry points  
much like a driver, and can be called from any other module.  In fact,  
the rbdw3 RBF driver calls into the DW3 subroutine module this way,  
and so does the clock module.  The DriveWire 3 has been totally  
modularized to facilitate extensions like the one you're contemplating.

The difficulty, as you noted, is polling over the bitbanger.  Here's  
what I've done as an experiment: I have a protocol extension to  
DriveWire 3 and rudimentary driver written that uses F$VIRQ to install  
a virtual interrupt service routine that hooks to the clock.  For some  
number of times per second, the clock driver will call the interrupt  
routine in my driver, which sends out a packet to the server to see if  
there is data available. The server responds back with one of two  
possible indications: (a) no data or (b) data available, and the data  
itself.  The driver then gets the data and processes this.

Note that this is not nearly as ideal as an interrupt drive mechanism  
(which is not possible at the speed the bitbanger is being pushed),  
but it does work, and a similar model can be used to do what you want  
done.  All you need to do is design your own driver and protocol, and  
extend the DriveWire server to honor that protocol.

Boisy

On Jul 6, 2009, at 1:15 PM, Aaron Wolfe wrote:

> On Mon, Jul 6, 2009 at 1:50 PM, William  
> Schaub<wschaub at steubentech.com> wrote:
>> Aaron Wolfe wrote:
>>
>> I once had a similar Idea. this may be possible if an API to the  
>> drivewire
>> routines could be exposed to developers on OS/9 you would have to  
>> extend the
>> drivewire server software to handle some new custom opcodes and  
>> pass traffic
>> back and forth. and you would have to do lots of polling but I  
>> think it
>> could be done. but as far as I know I don't know if boisy ever  
>> added any way
>> for a programmer to access the drivewire bit banger routines to  
>> extend the
>> system. (I'm still using drivewire V2.0)
>>
>>
>
> that's interesting, I had not considered using the drivewire interface
> to do this.  my current setup is completly incompatible with it, which
> is why I was planning on getting a 'real' drive interface of some kind
> to move forward.  the drivewire does provide both a disk system and a
> realtime clock to os9... providing a usable serial port would be a
> natural and very useful extension.
>
> currently, I terminate tcpip connections on a linux box running server
> code that handles all the sockets and communicates with the coco by
> way of a single ip connection to a terminal server.   the serial data
> is given a header that indicates which session it belongs to on the
> way in by my server code, and on the way out by the coco.  this allows
> multiple simultaneous sessions to the coco.  my poc code is running in
> basic (due to the limitations of my current setup) so the coco side is
> not multitasking, it is handling the events sequentially, limiting its
> usefulness to small things that can be done quickly, like chat rooms
> or very simple bbs type systems.  however if the sessions could
> terminate in devices under os9, this would become very nice for true
> multiuser scenarios running any kind of software.
>
> crude ascii:
>
> (internet)  === lots of ip connections ===> (linux server) --- one ip
> connection ---> (term server) --- one serial connection ---> (coco)
>
> (and it all actually works :)
>
> -Aaron
>
>
>
>>
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