Updating the firmware is the same process for Windows and Mac OS X computers.
1. Download the Myo Firmware file for your Myo armband here.
2. Connect your Myo to your computer with a USB cable. A removable drive will be mounted called "Myo"
3. Copy the Myo Firmware HEX file downloaded in step 1 to the "Myo" drive. (The INFO.TXT file is a hidden file)
4. After a few seconds the "Myo" drive will unmount from your computer, before reappearing again. During this process, the window showing the drive will close. Reopen the drive called "Myo". You should see a SUCCESS.txt file. If you do not, repeat step 3.
5. Once you have confirmed the SUCCESS.txt file appearing, disconnect your Myo from the computer. The LED will pulse a pale purple colour for a few seconds while the firmware update is initialized, then return to its previous connected or idle status.
Your Myo armband's firmware is now updated!