This works somewhat fine

PyVM is a virtual machine written in pure Python that runs Intel 8086/8088 machine code. No dependencies, no installation required.

Running tests

You may want to run the tests first. To do this, execute from the command line:

cd path/to/PyVM
python unittest_basic.py
python unittest_VM.py

Assembling your code

At the moment, PyVM can only execute flat binaries. You can assemble those with, for example, NASM:

nasm -f bin -o program.bin program.s

Then, execute the binary with PyVM:

import VM

vm = VM.VM(1024)  # a virtual machine with 1024 bytes of memory; you may need to increase this value

vm.execute_file("path/to/program.bin")  # this is what you've assembled at the previous step

Errors that may occur

If you decide to open an issue, please include a minimal, complete and verifiable example that reproduces the error and the traceback.

• Not enough memory supplied -> increase the amount of memory given to the VM

  Traceback (most recent call last):
    File "...", line 53, in <module>
      vm.execute_bytes(binary)
    File ".../VM/fetchLoop.py", line ..., in execute_bytes
      self.mem.set(offset, data)
    File ".../VM/Memory.py", line ..., in set
      assert offset + size in self.bounds
  AssertionError
  

• Unknown opcode -> please open an issue entitled Unknown opcode: [opcode in hex]

  ...
  ValueError: Unknown opcode: 0xf8
  

• The executable attempted to access a nonexistent memory location -> make sure your code absolutely cannot do this (that is, works fine after having been assembled, linked and run as a native executable), that there's enough memory supplied to the VM and open an issue entitled Invalid memory access.

  ...
     assert offset + size in self.bounds
  AssertionError
  

• Other errors -> please open an issue entitled accordingly

Features

• all 8-, 16- and 32-bit registers
• stack
• user memory
• flat memory model
• ~50% of 8086/8088 Intel processor's instruction set
• some basic prefixes
• execution of flat binaries and raw bytes

TODO

• add segments
• implement multiplication and division
• add more instructions
• add support for more binary formats