Input/ Output Block
This block features inputs and outputs supporting a wide range of signaling standards and interfaces. A basic Input/ Output block is shown below:
The buffers in the Input and output paths route the input and output signals to the internal logic and the output pads either directly or via a flip-flop. The buffer can be set to conform to various supported signaling standards which might even be user defined and externally set.
In any assembly line it is often the slowest segment which sets the overall production rate. Much in the same way, it is the route that takes the longest delay that eventually determines the performance of the entire electronic system. Thus routing algorithms are brought into place for the design of the most efficient paths to deliver optimum performance. Routing is on various levels like Local, between LUTs, flip-flops and the General Routing Matrix, General Purpose Routing between various CLBs, I/O Routing between I/O Blocks and CLBs, Dedicated Routing for a certain classes of signals for maximizing performance and Global Routing for distributing clocks and other signals with very high fanout.