What is pyMCU?
pyMCU is a micro-controller that can be used with python. There is custom software on the microchip that works in conjunction with the python module on the computer to operate much like a traditional microchip that you would normally load your code onto except this one allows you to drive that functionality realtime using python. Think of it as a hardware interface to the real world for your computer that you program with python.
Does pyMCU work without being connected to a computer?
Yes and No, pyMCU is intended to work while plugged into the computers USB port because python running on the computer is driving the functionality of the microchip as well as using the USB as the power source. That being said it is also possible to use pyMCU as a standard microchip breakout board and program the chip using ICSP with any of the commercial or free languages available for PIC microchips along with battery power and the board can work completely on its own but you will loose the designed intention of controlling the device with python and making it easy use so that option is really for more advanced users.
What operating systems does pyMCU work with?
pyMCU works with Windows, Linux, and OSX. pyMCU uses the FTDI USB to UART chip that provides drivers for all 3 OS's and python which is also available on all 3 OS's. Depending on the version of your OS there is a possibility of incompatibility with the drivers or a particular version of python please check the Installation Guide for further details.
Why not run python on the MCU instead of having it run on the computer?
While there has been some good progress getting python to run on the microcontroller (pyMite) it is still limited in functionality both by the limitations of the python implementation and the physical hardware limits of the microcontroller.
Running python on the computer side you don't have to worry about limited code space as you would on a microcontroller.
Using python in the interactive shell mode allows you to quickly try and debug various electronic components with instant feedback.
Running python on the computer also makes it quick and easy to try out different code without the process of compiling and flashing the microcontroller.