Cartilage: From One MUX To Runtime Spatial Reconfiguration

July 22, 2026

Cartilage makes local logic, routing, ownership, configuration, and regional replacement visible inside one spatial computing architecture.

Start Chapter 1 With One MUX And Build Toward LUT6

Build The Cartilage Spatial Circuit Workstation

The path begins with a selector whose wires you can see, follows the analog and physical machinery that keeps logic reliable, and arrives at a parent creating a bounded daughter machine in adjacent space.

Each chapter adds one necessary layer. Read the sequence in order, then open the running fabrics with the entire mechanism in view.

The FPGA and Verilog learning path builds LUT, register, testbench, synthesis, and place-and-route fluency. Cartilage then carries those foundations into explicit physical distribution, regional ownership, and runtime reconfiguration.

Progression from one visible multiplexer to stored truth tables and FPGA LUT4, LUT5, and LUT6 primitives
Original Greenforest I/O diagram for Chapter 1: one visible choice primitive grows into the lookup tables used across real FPGA families.

Build The Architecture One Chapter At A Time

  1. Logisim, The MUX, And LUT1 Through LUT6

    Expose the selector, grow it into stored truth tables, then connect LUT4 to Lattice iCE40 and LUT5/LUT6 to AMD/Xilinx configurable logic.

    2020 foundation: MUX Algebra writes local choice as a conditional, enumerates all 16 two-input Boolean functions, and defines the original four-bit configuration scheme.

    Hands-on companion: the physical MUX tiles embody inputs, constants, selectors, routes, intersections, and orientation as fabricated PCB parts for a proposed STEM/EE learning path. The tile alphabet supplies a tactile route into the wider Cartilage architecture.

  2. CMOS Inverters As Gain, Restoration, And Output Drive

    Move beneath Boolean symbols. A real inverter contributes a voltage-transfer curve, transition-region gain, noise margins, finite output current, and capacitive load. Restoring stages and sized drivers carry reliable logic across fanout.

  3. Clock, Event, And Reset Trees; H-Trees And Driver Grids

    Treat every high-fanout event as a physical distribution system. Buffer trees, H-shaped geometry, grids, and segmented regional networks trade skew, insertion delay, energy, metal, and locality across clocks, resets, configuration edges, and application events.

  4. Harel Statecharts And One-Hot Spatial State Machines

    Use Harel statecharts to express hierarchy, concurrency, and event-driven transitions. Give every one-hot state a visible storage location, then connect behavioral composition to a machine whose active state occupies space.

  5. Clock Regions And Timing Closure

    Close the machine in physical space: placement sets path length, buffers carry fanout, congestion redirects routes, clocks cross regional resources, and final delays satisfy setup and hold constraints.

  6. Metal Wires Are Part Of The Machine

    Replace free arrows with layers, vias, resistance, capacitance, direction, and finite routing capacity. Cartilage side-metals expose locality; physical implementation maps that locality onto real routing resources.

  7. OOP-Style Nested Components And Composition

    Give each component state, identity, and an interface while its parent composes children and preserves their identities. Cartilage turns that software intuition into a bounded child region, a local interface, and a configuration path inside the fabric.

  8. Runtime Instantiation In An Adjacent Region

    Watch a parent stream a complete image through a local reconfiguration port into a neighboring daughter region. New wire, intersection, constant, MUX, and port roles turn bounded replacement into dynamic reactivity on space.

Anchor Every Layer In Primary Sources

Each source connects one chapter to a maintained tool, official device manual, primary paper, or physical-design reference.

Circuits

Logisim-evolution

Use the maintained cross-platform logic design and simulation tool alongside the public multiplier’s legacy Logisim 2.7.1 circuit.

LUT4

Lattice iCE40 Technology Library

Read the official SB_LUT4 primitive and its exact 16-bit LUT_INIT address mapping.

LUT5 / LUT6

AMD UltraScale CLB Guide

Connect the official 6-input LUT and dual-LUT5 modes to their storage, carry, routing, and slice context.

Gain

MIT: Inverter Basics

Follow CMOS transfer characteristics, noise margins, and sizing into the restoring gain stage beneath digital logic.

Distribution

AMD UltraScale Clock Structure

Trace clock regions, horizontal spines, vertical and horizontal tracks, roots, leaf buffers, and segmented regional distribution.

Behavior

Harel's Statecharts Paper

Read the 1987 primary paper that introduced hierarchy, orthogonality, and event-driven behavior as one visual formalism.

Closure

AMD Timing-Closure Methodology

Use constraints, clocking, congestion, path delay, and skew to drive a placed and routed design into timing closure.

Metal

OpenROAD Parasitics Estimation

Estimate routing-layer resistance and capacitance with distinct clock and signal wire models after placement or global routing.

Put The Foundations Into The Running Fabric

Run it now

Open One-Slot Multiplier

Change two four-bit operands and watch the self-contained routed multiplier propagate through the visible WebGL fabric without an account or backend.

Open the workstation

Public Artifact And Private Circuit Authoring

See how the open multiplier leads into private editing, loading, saving, sharing, and browser, Raspberry Pi, and FPGA streaming work.

Read the marks

Cartilage Visual Language

Decode reconfiguration ports, crosses, constants, wire orientations, and MUX modes across a complete fabric render.

See composition

Nested Instantiation

Watch local ports install bounded daughter regions through serial replacement.

Inspect the core

Cartilage Core

Open the compact WebGL1 model, hardware paper, SystemVerilog RTL, Verilator testbench, and exact 252-bit installation.

Build what comes next

Cartilage Development Roadmap

Build renderer ergonomics, deterministic region roots, ownership overlap, recovery, simulator controls, saved circuits, and interactive lessons.

Read the architecture

Cartilage Compute Hardware Paper

Read the editable architecture paper for the local configuration protocol, cell roles, ownership boundary, runtime application behavior, and verification architecture.

Open the wider Cartilage run index for complete run packages, timelines, placement maps, and circuit traces.

Preserve The Running Lineage And Extend It Deliberately

The self-contained WebGL machines retain their original execution paths, while these articles supply modern context, mechanism, and navigation around them. The broader run index carries additional timelines, placement maps, and circuit traces beside this teaching sequence.

Every new chapter adds a clear construction, an attributable diagram or running machine, primary sources, and one deliberate next step. That discipline turns Cartilage into a coherent architecture for learning, use, and collaborative development.

Try Cartilage: Run the open one-slot multiplier.

To edit, load, save, share, and follow the browser, Raspberry Pi, and FPGA streaming work, request the private demo username and password on LinkedIn.