Questions about recompiling the programs written by Quartus II 9.1 with Quartus II 13

[Altera_Forum]

When recompile the programs written by Quartus II 9.1 with Quartus II 13.0 and programme the new POF file into the FPGA(EP1C12), I find that the FPGA does not work the same as being programmed with the POF file produced by Quartus II 9.1.  

So I wonder whether the POF file produced by Quartus II 13.0 is wrong. Are something of compiler of Quartus II 13.0 should be set up before recompiling programs written by Quartus II 9.1? Or 13.0 and 9.1 are not Compatible?  Looking forward to your help!

[Altera_Forum]

As far as I'm aware of, Quartus 13 doesn't support Cyclone I (EP1C12). So I wonder what you are doing at all.  

 If you want to maintain Cyclone I or Cyclone II projects, you'll need to keep a pre-Q13 version.

[Altera_Forum]

Asside from the issue FvM brought up - be aware that different compilers can produce different comilation results. So if you have asynchronous logic and/or poor timing specs, you should expect differences in performance.