Re: Re: Is xPL the ideal work-around? Need to access the LPT port from Mister House...

[Gerry Duprey <gerry@xxxxxxxxxxx>]

Howdy,

> Good points, but! Now the driver is limited to parallel printer ports.
I
> have a 8 input (optically isolated) & 8 output (relay)) internal
PC card. As
> well as a internal TTL based 48 I/O card.
> It would now be a shame to have the driver limited to LPT style of
ports and
> not be able to support the above cards.

This whole thing started off, as the subject still carries, as a request to
be able to send data to the LPT port and that is the direction I've been
following it.  So for me, this discussion really has been about accessing
these sorts of ports and writing binary data to them (serial and parallel).

I get what you are saying (about the 48 port thing), but in the case of
something that is this specialized, I'd imagine you'd be a lot better off
with a dedicated xPL driver for it.  I think that it is distinct enough
from
talking to serial and parallel ports that it should be considered
differently (the only commonality being that you control hardware by
writing
to memory locations -- something you could use to describe to talking to
network cards, video cards, disk drivers, etc).

I know that I cannot create a cross platform app that will allow direct,
low-level access to hardware in a computer.  Such a thing is going to
always
be very specific to at least hardware and possibly a hardware & O/S
combo.

Consider that even under Windows you'd need two different xPL apps. How you
access hardware varies even there -- that's why stuff written to hit ports
in Windows NT/2000/XP doesn't work under 95/98/Me -- same hardware, just
different OS's.

> Perhaps the driver should allow addressing either via the operating
system
> handle or via direct I/O?

Certainly, if you are running under Windows NT/2000/XP, you can continue to
use Johns xPLio server -- it should work for what you are talking about.
But I cannot create anything like that in Java (even if I could access
hardware addresses directly, there would be mondo complications in a cross
platform app).  What I'm pursuing is really trying to solve the more
narrowly focused initial thread requested.

If you really want a general xPL app that can poke any byte of RAM on a
computer, I think it might be better off taking a different tack and
schema.
Just my opinion on that though :-)

Gerry
--
Gerry Duprey
Ann Arbor, MI 48103
http://www.cdp1802.org