[Coco] Socat drivewire relay to CoCo1

[jon bird]

In article 
<CAA6uQZRrhJ=wREEHy9+9S6kD90j7w-xsOaN6dHbN2r-qhay5RQ at mail.gmail.com>, 
Aaron Wolfe <aawolfe at gmail.com> writes
>On Sat, Feb 28, 2015 at 6:21 AM, jon bird <news at onastick.clara.co.uk> 
>wrote:
>> Hi,
>>
>> Now I've got my CoCo 1 up and running again I thought I'd give 
>Drivewire
>> a go. A couple of initial queries then - I made the cable up iaw with
>> the diagram here:
>>
>> 
>http://www.cocopedia.com/wiki/index.php/Getting_Started_with_DriveWire
>>
> I'm not entirely sure of the significance of the CD/"turbo mode" 
option
> and there seems to be some differences in the baud rate you need to 
set
> the server end to - either 38400 or 57600. Currently the only
> configuration I get anything sensible with is 38400 with or without CD
> connected.
>

[...]

>The coco 1 is a bit of a special case because it cannot reliably
>operate at 57,600 bps (slow level shifters or some such hardware
>deficiency compared to coco 2).  Because of this, it must remain at
>38,400bps.  The double speed "turbo" mode using the CD pin is not
>possible as far as I know.  It is also sensitive to cable length, so
>make sure the serial cable is as short as possible.  Cabling and speed
>problems often manifest as checksum errors like you are seeing.
>
>To ensure the coco is operating at 38,400bps you need to use the
>correct ROM or DW binary on the coco, the special version for coco 1
>should only operate at 38,400.  Of course the serial port on the pc
>side should also be set to 38,400.  The DW server does this when it's
>told a coco 1 is connected, but since you're working over IP that will
>need to be done on the machine running socat.
>
>FWIW, I wrote DriveWire using a prolific adapter :)  Many people do
>have trouble with them, so that may be a factor in your configuration.
>However the checksum issue makes me suspect its either trying to work
>at 57,600 or the cable itself is causing trouble.

Thanks for the info. I am indeed using the CoCo 1 binary, the serial 
cable is ~30cm long. Given that it seems to work reliably in a "local" 
configuration it sounds unlikely that it is the cable itself causing the 
problem. Given the network traffic looks ok the only difference I can 
think of is the timing differences due to it sending over Ethernet.

As an aside though, I also have a CoCo 2 in the cupboard, it needs a bit 
of work before I can use it but (once I fix it) presumably that will 
then run at 56K, does that also need this "turbo mode" configuration on 
the serial cable?

A couple of other observations which I forgot to mention earlier, I 
couldn't actually get DW to work when connected directly to the Prolific 
adaptor. The first time around it generates a "Unsupported com operation 
whilst opening /dev/ttyUSB0", then repeated "Handler #0: Serial device 
in use" messages. Given that I don't intend to run DW in this 
configuration, it doesn't affect me but just thought I'd mention it in 
case there is a bug here.

Rgs,


Jon.

-- 
== jon bird - software engineer
== <reply to address _may_ be invalid, real mail below>
== <reduce rsi, stop using the shift key>
== posted as: news 'at' onastick 'dot' clara.co.uk