Altera Quartus Ii 8.1 Web Edition -windows- Free Download Repack -

: Supported 8.5-Gbps transceivers, 1.6-Gbps LVDS, and 400-MHz DDR memory. Design And Reuse System Requirements for Windows

The most reliable source is the Intel FPGA Software Download Center . You may need to navigate to the "Legacy" or "Archive" section to find version 8.1. Altera Quartus II 8.1 Web Edition -Windows- free download