Update README.md

more details on existing commercially available adapters

adapter/README.md

@@ -13,11 +13,20 @@ with the wiring when using the `rpi-rgb-led-matrix` code.
      As another option you can buy it from these locations not affiliated with this project.
      They are given to help you locate premade boards but no guarantees are given or implied:
      * https://www.electrodragon.com/product/rgb-matrix-panel-drive-board-raspberry-pi/
-       ($3/board, but fairly long and/or expensive shipping from HKG)
-     * The new HD board with angled connectors, is here: https://www.electrodragon.com/product/rgb-matrix-panel-drive-board-for-raspberry-pi-v2/ << **this is the recommended board for most users today**
+       ($3/board, but fairly long and/or expensive shipping from HKG). The old board includes 
+       support for an optional RTC (real time clock) which had to be disabled for most users 
+       who wanted 3 channels instead of an RTC.
+     * The new HD board with angled connectors (thinner footprint), is here: https://www.electrodragon.com/product/rgb-matrix-panel-drive-board-for-raspberry-pi-v2/ << **this is the recommended board for most users today**
+    ![RGB-Matrix-Panel-Drive-Board-For-Raspberry-Pi-V2-02-400x400](https://github.com/user-attachments/assets/713e2414-04f9-4fc3-86a2-cb576e29e057)
+
    * The [Passive-RPi1](./passive-rpi1) adapter board is to connect one panel to
      Raspberry Pi 1 with 26 GPIO pins.
 
+   * For completeness, Adafruit has a single channel active board here: 
+     https://www.adafruit.com/product/3211 although it is ultimately inferior to the 
+     electrodragon board, but it does ship quicker if you're in the US (note that you will
+     need special compile option or command line argument since it uses non standard wiring)
+
 ![Three Panels connected][three-panels]
 
 [three-panels]: ../img/three-parallel-panels-soic.jpg