Proteus 8.1 Portable 64 Bit ((better)) -

While portable versions are convenient, remember that . Official portable installation modes are available for licensed users to facilitate multi-machine working. If you are looking to explore the software for the first time, Labcenter offers a Free Demo Version which allows for full evaluation of schematic and PCB features, though it does not permit saving your own work. Proteus: PCB Design and Circuit Simulator Software

Minimum 3GB to 8GB of RAM, depending on the complexity of the simulation. Proteus 8.1 Portable 64 Bit

Labcenter offers a free Proteus 8 Demo . It has limitations (no save, no print), but it is safe and legal. There is also the Proteus 8 Student Edition , which is cheap and fully functional for non-commercial use. While portable versions are convenient, remember that