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+## Build instructions for Original Prusa i3 MK2/S/MM Firmware
+
+### Step 1 - Download and Install/Unpack Arduino
+
+Download and install the Arduino IDE. The most recent version 1.8.5 is available here:
+<a href="https://www.arduino.cc/en/Main/Software" target="_blank">https://www.arduino.cc/en/Main/Software</a>
+
+If you already use a different Arduino IDE version for other projects and don't want to upgrade to the latest release, you may want to install a stand-alone (ZIP file) version rather than using the "Windows Installer".
+
+### Step 2 - Prepare the Arduino toolchain
+
+1. Open the IDE
+2. Choose _File -> Preferences_ and set "Additional Boards Manager URLs" to the RAMBo repository:<br/> <a href="https:// raw.githubusercontent.com/ultimachine/ArduinoAddons/master/package_ultimachine_index.json" target="_blank">https:// raw.githubusercontent.com/ultimachine/ArduinoAddons/master/package_ultimachine_index.json</a>
+3. Select _Tools -> Boards -> Boards Manager_ and install the RAMBo board:<br/>"<small>**RepRap Arduino-compatible Mother Board (RAMBo)** by **UltiMachine**</small>"
+4. Close the IDE.
+5. Open the IDE and select **RAMBo** as target board from the _Tools -> Boards_ submenu.
+6. Close the IDE
+
+### Step 3 - Download PRUSA i3 MK2 Firmware
+
+You can either clone the prusa3d/Prusa-Firmware repository to a local directory or download the ZIP file from <a href="https://github.com/prusa3d/Prusa-Firmware/tree/MK2" target="_blank">https://github.com/prusa3d/Prusa-Firmware/tree/MK2</a> and unpack it in a local directory.
+
+Specific released versions of source code in either **.zip** or **.tar.gz** packages can be found here:
+<a href="https://github.com/prusa3d/Prusa-Firmware/releases" target="_blank">https://github.com/prusa3d/Prusa-Firmware/releases</a>
+
+### Step 4 - Configure the Printer Firmware - select variant
+
+The following configurations are available in the __Prusa-Firmware/Firmware/variants__ directory.
+(See **How-to-choose-firmware.pdf** for help choosing configuration.)
+
+* 1_75mm_MK1-RAMBo10a-E3Dv6full.h
+* 1_75mm_MK1-RAMBo13a-E3Dv6full.h
+* 1_75mm_MK2-MultiMaterial-RAMBo10a-E3Dv6full.h
+* 1_75mm_MK2-MultiMaterial-RAMBo13a-E3Dv6full.h
+* 1_75mm_MK2-RAMBo10a-E3Dv6full.h
+* 1_75mm_MK2-RAMBo13a-E3Dv6full.h
+
+Copy and rename the file representing your configuration to the ``Firmware`` directory as ``Configuration_prusa.h`` Example:
+> $ cp Firmware/variants/1_75mm_MK1-RAMBo13a-E3Dv6full.h Firmware/Configuration_prusa.h
+
+### Step 5 - Build the Firmware
+
+1. Open the IDE
+2. Load the firmware project with _File -> Open..._ Navigate to and open:<br/>
+ ``Prusa-Firmware/Firmware/Firmware.ino``
+3. Compile the firmware with _Sketch -> Verify/Compile (CTRL-R)_ --or--
+4. Export the compiled binary with _Sketch -> Export compiled Binary (CTRL-ALT-S)_.<br/>
+You will find the exported binary in ``Prusa-Firmware/Firmware/Firmware.ino.rambo.hex``
+
+
+### Step 6 - Upload the Firmware
+
+You can upload the new firmare to the printer by using either:
+
+* The Prusa3D Firmware Updater (download from <a href="https://www.prusa3d.com/drivers/" target="_blank">https://www.prusa3d.com/drivers/</a>)
+
+* Directly via the Arduino IDE...<br/>
+    Select _Tools -> Port_ and select the serial USB connection to the printer.<br/>
+    Select _Sketch -> Upload_ to build and flash the firmware.
+
+* Obtain the free utility: **avrdude** for your platform. Firmware may be uploaded either directly via command-line or using OctoPrint. Example command-line:
+>$ avrdude -v -p m2560 -c wiring -P /dev/ttyUSB0 -b 115200 -U "flash:w:**firmware.hex**:i" -D
+
+Happy printing!
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