I am having to support an old Cyclone III V6 design. The only source file I have seems to be AHDL in *.tdf format. What development tool do I need to support these old files and generate the *.rbf files?
The last version of Quartus to support Cyclone III was 13.1. Here's the device support list:https://dl.altera.com/devices/ There are links in the list to download the version you need. I have not used AHDL in more than 20 years but I think/assume Quartus still supports it. Good luck!
Yes the current versions of Quartus still support AHDL. I have a project in Quartus 16.1 that uses custom QSys components with some old AHDL *.tdf files and it works fine.