(An Example answer of the Virtex-6 family) The Configurable Logic Blocks(CLBs) are the main logic resources for Virtex 6 devices. One Virtex-6 CLB has up to 1412MHz toggle frequency. It contains two Virtex-6 slices. Each Virtex-6 slice contains: • Four 6-input LUTs or dual-output 5-input LUTs • Can be used as: Two 5-input lookup-table • 8 flip-flops • Arithmetic logic gates • Large multiplexers • Fast carry look-ahead chain • 128bits Shift registers (only on 1/3 SLICEM slice) • 256bits Distributed RAM (only on 1/3 SLICEM slice)