This is an Onramp VM in Python.
The Python VM is dozens of times slower than a handwritten machine code VM. The Onramp bootstrap with the Python VM takes several hours on a modern machine. I'm not sure if there is a way to fix this. Unfortunately Python is just extremely slow.
Both Python 2.7 and Python 3 are supported, although it is even slower on versions before 3.3 due to the lack of memoryview.cast().
Only the minimum necessary syscalls are implemented. In particular, it lacks any kind of terminal configuration so it is not capable of running Doom.
This is mostly only useful as a demonstration of an extremely simple VM that performs virtually no error checking. If you want an example of an Onramp VM to port to another language, this is a great place to start.