[Linux-parport] PC-to-PC parallel port cable

[Dave Strauss]

Most of these issues have been covered in this list before; see
for example http://www.cyberelk.net/tim/parport/archive/current/5769.html
and http://www.cyberelk.net/tim/parport/archive/current/5772.html.
The rest of this thread may also be of interest to you.

If you want to understand more about how the parallel port on PCs
works, I suggest this site:

  http://www.beyondlogic.org/

and in particular these pages:

  http://www.beyondlogic.org/spp/parallel.htm
  http://www.beyondlogic.org/parlcd/parlcd.htm
  http://www.beyondlogic.org/epp/epp.htm
  http://www.beyondlogic.org/ecp/ecp.htm

The documents are DOS-centric but they give a pretty good overview of
the standard parallel port hardware found in PCs.  Finally, if you
want to understand the standards behind ECP and EPP mode you can get
the IEEE1284 standard from ieee.org.

Whenever this issue comes up, I always have to ask why someone is
trying to connect two PCs together via the parallel port.  Why not
just connect them with an ethernet cable?  Unlike the parallel port,
ethernet was designed for bidirectional communications and the
software to do it is already there.

-- Dave Strauss

On Sat, 21 Feb 2004 19:27:53 -0800 (PST), Ravi Shah <shahravi20 at yahoo.com> wrote:
>  
>  Thanks for your response.
>  
>  I am sorry, but I am getting confused. Can you please explain, what
>  difference is it making? Now since you can connect two PCs using
>  SPP or nibble mode and share data, why not in ECP/EPP?
>  
>  There is a document ECP Specifications from Microsoft, where this
>  type of thing is getting done using a special cable (which
>  unfortunately is not available in market)?
>  
>  Thanks a lot for your help,
>  Ravi
>  
>  --- Dave Strauss <dstrauss at alum.mit.edu> wrote:
>  > On Sat, 21 Feb 2004 13:12:30 -0800 (PST), Ravi Shah <shahravi20 at yahoo.com> wrote:
>  > >  
>  > >  Hi,
>  > >  
>  > >  Does anybody know of a parallel port cable that can be used to
>  > >  connect two PCs through ECP/EPP protocol??
>  > >  
>  > >  Thanks in advance for help,
>  > >  Ravi
>  > >  
>  > 
>  > You basically can't do that, because ECP and EPP are both master/slave
>  > protocols -- from both the hardware and the software point of view --
>  > and a PC only contains the hardware to do the master end.  You can
>  > use a LapLink parallel port cable to connect two PCs, but you can't
>  > do ECP or EPP over the cable.
>  > 
>  > -- Dave Strauss
>  
>  
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