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rtl/server_dispatch_unit.sv — Server Dispatch Unit (SDU, historical)

The original opcode router, superseded by noc_router.sv in v3. Not instantiated anywhere in the current design — kept in the tree purely for reference/history, since it's functionally identical to noc_router.sv (same routing table, same cpu_accept pulse convention) and documents where that convention came from. See progression.md for the v1→v3 history.

Where it fits

Nowhere, currently. If you're reading RTL and see server_dispatch_unit, you're looking at the pre-NoC-router SoC (v1/v2) shape — the live router is noc_router.sv, instantiated by base_die_top.sv.

Ports

Identical shape to noc_router.sv:

Direction Name Width Description
in clk, rst_n 1, 1 Clock / reset
in net_valid 1 Incoming instruction valid
out net_ready 1 Backpressure to the network source
in net_instruction 32 Incoming instruction word
out cpu_valid 1 CPU dispatch valid
out cpu_accept 1 1-cycle combinational pulse: instruction accepted for CPU
in cpu_ready 1 CPU pipeline ready
out cpu_instruction 32 CPU-bound instruction
out gpu_valid 1 GPU dispatch valid
in gpu_ready 1 GPU co-processor ready
out gpu_instruction 32 GPU-bound instruction
out npu_valid 1 NPU dispatch valid
in npu_ready 1 NPU ready
out npu_instruction 32 NPU-bound instruction

Functionality

Same routing decode matrix as noc_router.sv (0x37/0x17/0x6F/0x67/0x63/0x03/0x23/0x13/0x33 → CPU, 0x57 → GPU, 0x6B → NPU, else dropped), same cpu_accept single-pulse semantics, same backpressure equation. The two files diverged only in naming/comments as the project renamed "SDU" to "NoC router" once the UCIe/chiplet framing made "network-on-chip" the more accurate term for what this module does.

Example

See noc_router.md — the behavior is identical; this file is the historical name for the same mechanism.

  • noc_router.md — the module that actually runs today
  • sdu.md — the original prose writeup of this module (routing table, handshake protocol, cpu_accept pulse)
  • progression.md — v3 "NoC Router" section documents the rename/replacement