How to find suitable primitive for CycloneII?

You can find the primitive by right-click on a new opened verilog.v file, Insert Template > Verilog HDL > Altera Primitives.

Or you can refer to the document "Designing with Low-Level Primitives"

https://www.intel.com/content/dam/www/programmable/us/en/pdfs/literature/ug/ug_low_level.pdf

You may checkout this webpage for supported buffer primitives.

https://www.intel.com/content/www/us/en/programmable/quartushelp/13.0/mergedProjects/hdl/prim/prim_list.htmhttps://www.intel.com/content/www/us/en/programmable/quartushelp/13.0/mergedProjects/hdl/prim/prim_file_alt_inbuf.htm

Best Regards,

Richard Tan

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