: A highly popular, free, open-source tool with robust 3D viewing and library management.
If you need to open old Protel files (.pcb, .sch): protel advanced pcb 2.8 download
: There is no longer an official download link from the manufacturer. Altium only provides documentation and installers for more recent versions (typically version 15.1 and newer). Title: The Digital Archaeology of EDA: A Technical
is the definitive "old school" tool. Released in the mid-90s, this version was a staple for designers before the company evolved into Unlocking the Power of Protel Advanced PCB 2