Quartus versions coexisting

[Altera_Forum]

I have a PC with Quartus II V5.0 installed with SOPC Builder and NIOS II all of which runs under a Fixed PC license using a USB dongle. I would like to install Quartus V8.1 Web edition with SOPC. Can I install the new web edition without affecting any of the V5.0 installs? I have one project that needs the V5.0 stuff but I would like to start working with the Cyclone III under the latest Quartus. Of course the budget will not support purchasing another computer or a new Quartus subscription just now. 

 Thanks

[Altera_Forum]

yes, Quartus versions exist pretty well together. 

 if you're using SOPC Builder or DSP Builder you may need to mind your environment variables like QUARTUS_ROOTDIR, SOPC_BUILDER_PATH, etc.

[Altera_Forum]

Sure, 

 Just install in a diferent directory. You will not be able to use the NIOS II Procieeor, but SOPC will work just fine without it.  When switching back from the 8.1 tools to the 5.0 tools, just be sure to Launch (and close) the Quartus II 5.0 tools once before you start the NIOS II IDE, as there are some pointers that need to get set in the background and running Quartus II will set them for you.  Good luck, Avatar

[Altera_Forum]

If you use just Quartus, there is no problem having multiple versions installed simultaneously and going back and forth between versions. You simply start Quartus normally whenever you change versions. 

 If you use SOPC Builder and Nios tools, you have to be more careful and have to remember to change environment variables. When you start Quartus, it sets the QUARTUS_ROOTDIR environment variable automatically to point to the installation currently in use. Before you start SOPC Builder or Nios tools, make sure other environment variables point to the correct location.  When I install a new copy of the tools, I save off my environment variables. (I simply run "set > my_filename.txt" in a Command Prompt window to save everything.) When I am going to change to a different version that is already installed, I manually change the relevant variables other than QUARTUS_ROOTDIR to the values needed for the version I'm switching to. What variables are used has changed between version 5.0 and version 8.1.  This is documented at http://www.altera.com/support/kdb/solutions/rd03082007_165.html. I don't know whether that's the newest on-line reference. Altera_Tool_Switch.bat is mentioned there. I've never used it. It's easy enough to change one or two variables manually, and I know for sure what I'm doing if I do it manually.

[Altera_Forum]

Thanks everyone. That helped a lot.