LEGACY: older hexapod sketches (Hexapod_NEW, HexapodRobot)

From https://mangavalk.com/Hexapod/Hexapod @ 7945005 (its Hexapod_Teensy
is identical to the copy already in LEGACY). Earlier electronics
generation: on-board IK driving an external SSC-32-style servo
controller. Notes on what still applies are in CLAUDE.md.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

2026-current/CLAUDE.md

@@ -16,7 +16,9 @@ sim/                        robot firmware -> hexapod_sim.dll (CMake + g++), hea
 Hexapod_Simulation_Unity/   Unity 6000.6 project that loads the DLL (Assets/HexapodSim/)
 LEGACY/                     owner's older material for reference (remote/remote.HMI = old Nextion UI, 6 pages;
                             remote/teensy/ = old remote sketch from https://mangavalk.com/Hexapod/remote.git @ 492dece;
-                            Hexapod_Teensy/ = old robot sketch: servo passthrough only, no IK - see "Old robot sketch" below)
+                            Hexapod_Teensy/ = old robot sketch: servo passthrough only, no IK - see "Old robot sketch" below;
+                            Hexapod_NEW/, HexapodRobot/ = older generations with their own IK, driving an external
+                            SSC-32-style servo controller - all three from https://mangavalk.com/Hexapod/Hexapod @ 7945005)
 scripts/                    PlatformIO helper
 ```
 
@@ -320,6 +322,19 @@ Robot (`robot/README.md` has detail):
     - tibia servo = −tibia (right), 180 + tibia (left), so 90 = knee bent
       90°.
   - All of this is now in `Config.h` `SERVOS` (see "Servos" above).
+- **Older sketches (`LEGACY/Hexapod_NEW/`, `LEGACY/HexapodRobot/`, 2014–2016
+  era)**: an earlier electronics generation. They did IK on the board and
+  sent `#n Pxxxx … T0` text commands over `Serial1` to an external
+  SSC-32-style servo controller (channels 0–9 and 16–24).
+  - **Femur range:** it was already narrower there (600–2400 µs coxa/tibia,
+    960–2100 µs femur over 0–180°), which corroborates the ≈6.7 µs/° femur
+    in `SERVOS`.
+  - **Links:** femur 10, tibia 15 (cm), with no coxa length in that IK.
+  - **Hip layout comment in `Hexapod_NEW/HexapodClass.h`:** width 9.5 cm
+    (front/rear) and 14 cm (middle), 10 cm front-to-middle-to-rear. The
+    Unity model has 10 / 13 / 10. Whichever chassis is current, measure
+    before trusting `LEG_MOUNT_*`.
+  - Nothing else from them applies to the current Teensy 3.6 hardware.
 - `RobotIMU.cpp` reads `(Wire.read() << 8) | Wire.read()`, and C++ leaves
   the order of those two calls unspecified (fixed in the remote's copy).
 - Heading for mode B is open-loop (integrated commanded ω). Fusing IMU yaw