Hello, My apologies for not replying sooner. I have only just found out that you responded. I have been dealing with another responder but have had no satisfactory answer.
I finally discovered that, when I try to read data from an EEPROM, the reading instance records X"FF". Initially I tried a simple write/read using primitive bidirectional pin. I used this about 15 years ago with Quartus 7.2 with no problem. However this did not work with Q13.1 so I thought maybe the newer version needed a buffer. I added the ALT_IOBUF but with no succees so I went further and added a bus to the buffer reading output. I received the correct data and yet the instance (sat on the same bus) still gives all highs. (I read the input and sent it out on some test pins).
If you wish, I can send .zips of the .bdf, .vhd and .qsf files and others if necessary. I would also mention I tried Quartus Prime lite and 13.1 on both Windows 10 and 11 just in case there was a problem with either but there was no difference. I use a'scope for all diagnosis having never having used software diagnostics.
Regards
Ken