Direct control of parallel port data lines

Steve O'Hara-Smith steve at
Sat Apr 4 21:05:28 UTC 2020

On Sat, 4 Apr 2020 20:47:27 +0200
Polytropon <freebsd at> wrote:

> For an "external relay control unit", I need to activate
> certain lines of the parallel port. I wish to address
> the 8 output lines of the port. How is this done on
> FreeBSD?


> If possible, I want to use C for this task. I checked
> "man ppc" and "man ppi", but I don't find their content
> convincing, probably not what I'm looking for.
> What am I _actually_ looking for?

	ppi is exactly what you are looking for, but it will be strange
given where you're coming from. There is a huge difference between a
protected mode multi-tasking OS like FreeBSD and a real mode program loader
like DOS when it gets to this kind of thing.

Steve O'Hara-Smith <steve at>

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