1. Purpose and scope
The fabric is the product. Its logic block, routing and memory decide how much of a customer's design fits, how fast it runs and how much power it uses, and none of that can be judged from the hardware alone. A fabric is only as good as the software that maps designs onto it, so this stage judges candidate fabrics the way customers will meet them: by running benchmark designs through placement and routing and measuring the result.
The stage chooses the logic block, with its look-up tables, carry chains, registers and local routing; the routing architecture, with its wire lengths, switch patterns and connection to the logic blocks; the block memories and arithmetic blocks and how they sit in columns among the logic; the clock network; and the input and output structure. It also confirms that the process and the configuration memory technology can deliver the fabric, through the first technical readiness review.
Three gates close the stage. The TR1 technology feasibility review shows the process, configuration memory, critical hard IP and package can meet the targets. The fabric architecture freeze baselines the fabric. The product plan agrees members, order, software scope, cost and schedule, and commits development.
Software engineers are full members of the architecture team here. A routing pattern the router cannot use well, or a logic block the packer cannot fill, wastes silicon however elegant it looks on paper.
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