what does tri1, tri0

I'm pretty sure Quartus ignores tri1/tri0 directives.

However, with regards to what you're trying to do with your DE2 board - you don't have any internal pull-down options anyway.

You don't say which flavour of DE2. However, for the Cyclone II version there is no option for any pulls in the FPGA. I/O pins have weak pull-ups active before and during configuration. From the Cyclone II datasheet:

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In user mode, the user I/O pins no longer have weak pull-up resistors and function as assigned in your design.

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It's a similar story for the Cyclone IV DE2 boards:

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All I/O pins have an option to enable weak pull-up except the configuration, test, and JTAG pins. The weak pull-down feature is only available for JTAG TCK.

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So, unfortunately, there is no option for internal pull-downs with the hardware you're using.

Cheers,

Alex