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Re: Foolish Me...
Scott Laird writes:
> It's alternating one line, at more like 10 Hz on my system. I don't
> have the output handy, but if you watch a trace of the QuickCam program
> in Wine, you'll see that it ignores this stream anyway -- it sends a
> reset and waits for an acknoledgement.
Fortunately, we're running over a real operating system, so we can
just check /proc/ioports to see if a parallel port is available. If
it is, then we read the status register for a second and see if we see
the expected bits wiggling. If not, try another parallel port address.
> Here's the beginning, with the
> first part of the brightness command.
>
> IO: 0x0020 (1 bytes) to port 0x37a
> IO: 0x0075 (1 bytes) to port 0x378
> IO: read from port 0x378, res = 0x0075
Note how they're setting the port to input mode, then they're
outputting a known value to the output port? I'm pretty sure that
they're doing this to see if the parallel port is bidirectional. I
suspect that, if you read back something *other* than 0x75, that the
port is bidirectional. Anybody have a bidirectional parallel port to
test this theory?
-russ <nelson@crynwr.com> http://www.crynwr.com/~nelson
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