How can I switch to different tool versions of Nios II and Quartus II without reinstallation? - How can I switch to different tool versions of Nios II and Quartus II without reinstallation? Description Using Previously Installed Versions of the Nios® II EDS and Quartus® II Tools SOPC Builder and the Nios II IDE refer to the most recently installed version of components (such as the Nios II processor and peripherals) and their software drivers. To revert to a prior version of the Nios II development tools, you can reinstall the previous version of tools or modify the following environment variables. . SOPC_BUILDER_PATH - Ensure that SOPC_BUILDER_PATH points to the installation directory of the desired Nios II version and no other Nios II versions. SOPC_BUILDER_PATH should also contain the paths of other IP, separated by a " ". . SOPC_BUILDER_PATH_< version > - Ensure that SOPC_BUILDER_PATH_< version > points to the installation directory of the corresponding Nios II version. This is necessary only for versions 6.0 and 5.1. Exclude the period in <version>, for example, use SOPC_BUILDER_PATH_60 . SOPC_KIT_NIOS2 - Ensure SOPC_KIT_NIOS2 points to the installation directory of the desired Nios II version and no other Nios II versions. Finally, launch the corresponding version of Quartus II to ensure that the QUARTUS_ROOTDIR environment variable is updated. Then exit Quartus II before using any tools in the switched version, including Quartus II. For the Windows version, there is a batch script called Altera_Tool_Switch.bat, along with a special version of setenv.exe which can update system variables. They are available in the zip file Altera_Tool_Switch.zip . Related Articles Why do I receive the following error when trying to generate my SOPC Builder system: Generator program for module 'cpu' did NOT run successfully? Why do I get 'Severe' errors while using the Nios II Software Build tools? Custom Fields values: ['novalue'] Troubleshooting novalue False ['novalue'] ['novalue'] novalue novalue ['Programmable Logic Devices'] ['novalue'] ['novalue'] ['novalue']