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     The Spartan-II family is based on the Virtex 
      family architecture, while the Spartan and Spartan-XL families are based 
      on the XC4000 Series architecture. The 2.5V Spartan-II devices are a cost-optimized 
      Virtex architecture combining 0.22u transistors for 5V compatibility with 
      0.18u interconnect. The 5V Spartan devices combine 0.5u transistors, required 
      for the 5V supply, with 0.35u interconnect. Meanwhile, the 3.3V Spartan-XL 
      devices have 0.35u transistors, with a special I/O design for 100% 5V I/O 
      compatibility, and 0.25u interconnect. While the Spartan and Spartan-XL 
      families are footprint compatible with common packages within the series, 
      the Spartan-II family is not footprint compatible with the prior Spartan 
      Series members.  |