Installing MicroPython on the ESP8266

Check the port it is attached to in Device Manager. Download the firmware from the MicroPython downloads page.
Open a Command Prompt and do the following:

pip install esptool

# erase the flash

esptool.py --chip esp8266 erase_flash

# For the HUZZAH ESP8266 breakout buttons for GPIO0 and RESET are built in to the board
# Hold GPIO0 down, then press and release RESET (while still holding GPIO0),
# and finally release GPIO0

# install the firmware
esptool.py --chip esp8266 --port COM3 write_flash --flash_mode dio \
   --flash_size detect 0x0 esp8266-20190529-v1.11.bin

Full info on the Adafruit HUZZAH ESP8266 breakout on the Adafruit website.
Full info on MicroPython here.
Connection to the REPL over the serial prompt is at baudrate 115200 using Putty.
Note that the USB to UART serial console cable is connected as follows:

• n/a
• White - Tx
• Green - Rx
• Red - V+
• n/a
• Black - GND