I am almost certain that my Quartus II web 13.1 program creates RTL schematics with errors in them. (I have not upgraded the installation afterwards because my computer is offline!).

Thank you KhaiY, but I can't do that because I need my Quartus II 13.1 version because of still supporting the older Spartan 3 FPGA's. Yesterday I was not being able to download the upgrade files for version 13.1 because they seemed hidden somehow.

But today the download links to both upgrade files (930MB and 407.8MB) worked, so it seems that the upgrade is going to work now. And I hope that it will remove the RTL schematic bug where "1000" is seen as 4'h1 instead of 4'h8 in the Equation symbols.

Thanks!

PS: after upgrade and a first test the error is fixed GREAT!

I however still found a strange RTL result in an Excess3 converter.