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[aprssig] Re: Agw tracker and Agw packet engine

Dave Baxter dave at emv.co.uk
Tue Jan 16 10:03:50 UTC 2007


Some XP systems will let you use DOS app's and get to what it provides
you in the way of ports, but my guess is they are not updated to SP2 and
later etc.

Also, it depends a great deal, how the system policies are set, as well
as how the application uses the ports.  If it's direct fiddling of the
hardware, absolutely no way!  All NT based systems will spit feathers at
you and prevent you from doing that.  Unless you have a third party I/O
reservation driver, such as SmallPort and the like installed.

Via "standard" BIOS calls, maybe.  Via DOS system calls would be the
best bet, but you are still several layers away from the port itself,
and the access timing will be all screwey for the normal stuff, let
alone waggling handshake lines!...

Windows 2000 likewise.  We had a situation here, with that.  Prior to
Service Pack 4, we used to run all sorts of tools and utilities to mess
with our products via RS232 and LPT ports and the command line
interface.  After SP4 (but immediately, strangely) we gradualy lost the
ability to use COM and LPT ports in the "cmd" DOS like environment.

Personally, I have never had LPT or COM port access on this XP laptop
from the "Cmd" screen.  It has a real LPT port, but only USB for
anything else.  It's also fully "up to date" re updates etc, and the
background policies are set and managed from our office server.  That
has more control of this machines settings, than I do, and I'm sitting
in front of it!...

As earlier, there are several third party I/O port "reservation" drivers
about.  You tell them what ports you want to use, and they make them
their own as far as windows is concernd, you then call them for as real
time access as you will get.  But, again, you are still several software
layers away from the port itself.

Sometimes (rare) you can use those drivers to "own" a port, and fiddle
with it directly, but you have to write the code to do that, it will not
do it for existing DOS programs, some Win9x yes, but not DOS..

Also, re soundcard decoders.  Not all "Soundcards" are equal either.
Real hardware with the appropriate drivers (Soundblaster etc) will
always work better than the many software driven cards, where the
hardware is just basic (if fast) A/D, and all the codec functionality is
in the driver, not in dedicated DSP like many of the older, and newer
"high end" cards.

Has to be said, that for many, the default software driven soundcard,
does seem to work remarkably well, nearly all of the time.  Any
dificulties..  USB based devices are cheap now, and provide good results
too.

Enjoy.

Dave G0WBX.

> -----Original Message-----
> From: Mark Fellhauer [mailto:sparkfel at qwest.net] 
> Sent: Monday, January 15, 2007 6:15 AM
> To: TAPR APRS Mailing List
> Subject: [aprssig] Re: Agw tracker and Agw packet engine
> 
> At 11:31 AM 1/14/2007, Stephen H. Smith wrote:
> 
> Interesting.  It's funny how so many people say serial ports 
> don't work under XP in DOS, but I've run Trunker (in a DOS 
> Box) on several XP machines, using a very simple two-level 
> data slicer.  It also works with other DOS-based decoder 
> software for ACARS, POCSAG, etc.
> 
> I will admit, most soundcard based decoders work well and are 
> generally easier to set up.
> 
> 73,
> 
> Mark

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