I have a strange ongoing problem with my laptop. It's a single-core CPU with a top speed of 1.6Ghz and I use it for everything including programming old custom hardware through serial and parallel ports.

I'm running slackware 13 (Linux).

If I turn ACPI on then the fan problem goes away if I choose to run the system at a slower CPU speed, however when I try using the parallel port to program old hardware with ACPI on, then programming fails at least 50% of the time.

If however I disable ACPI completely in linux, then programming for the parallel port works completely, however my system reports the max CPU speed being used, and running some applications like Firefox makes my fan continuously go.

In my bios, I have no options for configuring the parallel port. and my computer is Latitude D600.

I already have the port setup in AT/SPP mode in the bios which is what the external hardware needs in order to be programmed.

Is there a way in Linux I can set it up so the fan does not constantly run from running todays applications and at the same time the parallel port works? I don't mind if it involves installing an additional driver that works or configuring something else in a linux config file.

OK, so what's happening here is that without ACPI support enabled, your processor is constantly running at full speed, and never entering any idle states. THis means that it is constantly generating heat, and what the system firmware is doing (keeping the fan running at max speed) is the correct behavior (because it's far better to be noisy than let your CPU fry itself).

As far as the parallel port not working, the ACPI tables probably have the region of memory that it's mapped to marked in such a way that the parallel port driver in Linux won't bind to it. If this is the case, then it is theoretically possible to by overriding the ACPI tables. However, doing that is very risky, you're essentially manipulating parts of the firmware that are responsible for making sure the system doesn't destroy itself by accident, so getting things wrong may brick the system. Unfortunately, I have no experience doing this myself, so I can't really provide any advice about how to go about doing it.

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