Official Cadence downloads no longer offer version 9.1. You may find it on academic software archives, old CD images, or third-party sites (e.g., Internet Archive, EDA board forums). Many sources may contain malware or be incompatible with modern Windows.
: A widely used, high-performance SPICE simulator provided for free by Analog Devices. pspice 9.1 student version free download
: Another legacy option sometimes suggested for beginners in DIY electronics communities . Official Cadence downloads no longer offer version 9