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RE: [avrdude-dev] Verify errors,

From: Rune Christensen
Subject: RE: [avrdude-dev] Verify errors,
Date: Tue, 22 Jul 2003 17:37:17 +0200

Win 95/98 don't have security levels as Win NT/XP.

In Win 95/98 user programs have free access to the hardware.
In Win NT/XP only kernel/system have access to the hardware.

GiveIO gives user programs free access to the hardware.
It removes the security by changing the access rights to the
hardware so the user programs have direct in/out access.

I have found this link
about allocate and free a parallelport under Windows.

Best Regards
Rune Christensen

Message: 1
Date: Mon, 21 Jul 2003 15:38:52 GMT
From: "E. Weddington" <address@hidden>
Subject: RE: [avrdude-dev] Verify errors,
To: address@hidden, <address@hidden>
Message-ID: <address@hidden>

> It would be easy to assume a problem with the printer
port, or driver
> software, though I would imacine that it is just being
bit banged using a
> direct access control.

AFAIK, it's bit banged using direct access control.

> So, is Win 2k interrupting this (a bit naughty since I
imaginge the resource
> is reserved when avrdude runs.)
> Oh, no it isn't I hear you cry and, after a quick test,
it isn't!
> I can run avr dude to program a chip, then run pony prog
and tell that to
> program as well! argg!
> I guess giveio accesses memory directly and doesn't use
the API or tell
> windows that the port is in use.

Correct, AFAIK.

> I do however have legasy plug and play detection turned
off in the settings
> for the printer port, but who knows what else windows
might do?
> The other option is that the way the timing is done isn't
accurate. Or the
> way timing is done varies between machines (Perhaps a
difference in a DLL or
> in the OS?

As this configuration (avrdude, parallel programming,
windows platform) hasn't been extensively tested (or
reported on), I don't want to say that it's exclusive to
any particular Windows OS version.

Though according to what I remember reading about parallel
port access, is that the giveio driver is required on the
Windows NT/XP branch and is not required on 95/98. There is
a fundamental difference in how the OS controls/interacts
with the parallel port. So I would make a guess and say
that it affects NT/XP/giveio.

Search on the net about giveio. From what I know, it's a
very simple driver and does not really interact with
Windows to gain exclusive lock on the port. And I've heard
that Windows XP does stuff like constantly ping the
parallel port, looking for a printer, which seriously
interferes with programming.

Unfortunately, to my knowledge, the giveio driver was the
only one out there that was useable, with ok licensing, and
was being used in other open source projects. However,
there seems to be issues with it, especially playing well
with others.

What is really needed is a new Windows device driver, that
is designed to work well with other parallel port drivers
and Windows (NT and XP), and designed for the kind of
software that needs exclusive control over all parallel
port pins. Most parallel port drivers and even the Windows
API from what I can tell, just assume that the only thing
hooking up to the parallel port is a printer. :-/


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