[Coco] rs232/bitbanger in MESS?

[Aaron Wolfe]

On Wed, Dec 2, 2009 at 6:39 PM, Robert Gault
<robert.gault at worldnet.att.net> wrote:
> John W. Linville wrote:
>>
>> On Tue, Dec 01, 2009 at 06:18:28PM -0500, Aaron Wolfe wrote:
>>
>>> I'm going to keep messing with this (pun intended) :)  Would be very
>>> useful to have a serial port in an emulator.
>>
>> That's pretty much what that code I sent you does, although it
>> doesn't pretend to be a 6551.  It does however handle a couple of
>> addresses in the emulated address space and connects them to a PTY
>> on the Linux side.  I find it very useful. :-)
>>
>> The MESS 6551 emulation seems to be modeling the behavior of the
>> 6551 as seen by the CPU.  But like you, I could never see that it
>> actually did anything to communicate outside of the emulator itself.
>> I don't know how that is useful to anyone other than as an exercise
>> in hardware emulation, but whatever...
>>
>> It probably wouldn't take much effort to take the code I sent you and
>> refactor it to more closely model the "user interface" (i.e. register
>> set) of the 6551 to that you could use 6551-aware CoCo programs to
>> talk to the outside world unmodified.  It's just a SMOP... :-)
>>
>> John
>
> I've got a question about this in to the MESS team but in the meantime ....
>
> MESS permits sending data through the bitbanger but you can only attach
> files that emulate printers. Clearly the data sent to $FF20 bit-1 is going
> out of MESS but the main question is it going only to a file emulating a
> printer or is it also going to the printer port?
>

this is interesting.. in a "real" OS like Linux, or OS-9, or a modern
Mac, a file and a printer port can be used mostly interchangeably..
so if it can send bitbanger output to a file, it can by definition
also send it to a printer port.  I'm going to look into that further,
since it may be that half of what I'd like to do (the output side) is
already there.

> If MESS sends data to both the PC printer port as well as files, then we can
> build printer to serial cables and talk to external hardware.
>
> --
> Coco mailing list
> Coco at maltedmedia.com
> http://five.pairlist.net/mailman/listinfo/coco
>