How DE2 communicate with PS/2

Hi everybody.

I have a Assignments : DE2 peripheral interface discovery .

And this subject is :How DE2 communicate with PS/2.

I try to search in the internet but I can't find the related documents.I fell difficult to make it.So , Can you help me?

what is the first thing I should do? And Where Can I get the related documents?

If I want to build a nios_system to implement(DE2 communicate with PS/2) by SOPC builder, what should I do?

Thank you for reading.

Sincerely!