Add pictures and some history for the prototypes

Fix typos in readme

README.md

@@ -31,7 +31,7 @@ developed.
 1. Clone this repository:
 2. Open the project file (`hw/tk1.kicad_pro`) in KiCad.
 
-alternativly download a release to get the generated output (Gerber,
+alternatively download a release to get the generated output (Gerber,
 schematics etc.) to be viewed in your preferred tool.
 
 ## KiCad and tools
@@ -44,7 +44,7 @@ The KiBot flow can be run locally using the Make target
 make run-kibot
 ```
 
-the prerequisits are `Podman`. `Docker` can also be used, see the
+the prerequisites are `Podman`. `Docker` can also be used, see the
 Makefile for details.
 
 

prototypes/mta1-usb-dev/README.md

@@ -0,0 +1,29 @@
+# mta1-usb-dev
+
+![](/mta1-usb-dev.jpg)
+
+This is the original TKey design, intended as a development platform.
+It is a larger PCB, that connects to a PC via a USB C cable.
+
+Main features:
+- 2 ICE40 FPGAs.
+
+- The first ICE40 (Interface FPGA) is connected to a USB C plug, and
+is loaded with a gateware that contains a soft USB device. This
+gateware acts as an USB-to-GPIO interface to the second ICE40.
+
+- The second ICE40 (application FPGA) is loaded with a RISC-V soft
+core containing the security firmware. User applications are run on
+this gateware.
+
+- The second ICE40 also has an input button for user presenence
+detection.
+
+- An FTDI module is included for programming both the Application and
+Interface FPGAs.
+
+- Both ICE40s can be configured to boot from included SPI flash
+memories, NVCM, or be live programmed from the FTDI module.
+
+- All GPIO lines between the two FPGAs, as well as all programming
+signals, are exposed on 0.1" headers for probing.