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Omnivore 2.0 (pre-release, very very alpha version)


Omnivore - the retrocomputing reverse engineering toolbox

Omnivore is a cross-platform app for modern hardware (running linux, MacOS and Windows) to work with executables or media images of Atari 8-bit, Apple ][+, and other retrocomputer machines and game consoles.

Features include (in various states of operation at the moment):

  • emulator with debugger (see below)
  • binary editor
  • disassembler (6502, 65C02, 6809, and many other 8-bit CPU architectures)
  • 6502 cross-assembler (ATasm, uses MAC/65 syntox)
  • graphics editor
  • map editor
  • Jumpman level editor (Atari 8-bit platform only)


Omnivore provides unified front-end to several 8-bit CPU and system emulators to provide a common set of control methods for both normal operation and debugging purposes. This is used as the basis for the emulation support in Omnivore.

Currently available are:

  • libatari800, an embedded port of the atari800 emulator
  • lib6502, a generic 6502 emulator based on David Buchanan's 6502-emu
  • crabapple, a thin layer atop of lib6502 that provides some (tiny, small amount of) Apple ][+ compatibility

The debugger includes:

  • rewind capability to return to previous point of emulation
  • debugger able to step forward (and, soon, backward)
  • change any portion of memory or processor state
  • CPU instruction history browser
  • memory access visualizer
  • memory map labels, used for disassembler
  • customizable memory viewer using labels and data types

A Tribute

While producing the Player/Missile podcast, I have had many ideas about hacking code on the 8-bits like I used to as a kid. One of the tools I had was the Omnimon system monitor board by CDY Consulting, an add-on board for the Atari 800 that provided a ROM-resident monitor similar to what was provided in the Apple ][+ hardware. In fact, I originally named this program Omnimon but felt that would be too confusing as there are people in the 8-bit community who still use the original Omnimon hardware. Using the prefix "Omni-" is my tribute to all the fun I had with the Omnimon hardware.

How To Run Omnivore

Omnivore 2.0 is still under heavy development. When it gets to a more stable state, I will create binaries for Windows and MacOS. These instructions will be for that time.

Windows & MacOS

Binaries are available for Windows 7 and later (64-bit only) and Mac OS X 10.9 and later and at the home page or directly through the github releases page.

Linux (or Using a Virtual Environment)

Binaries for linux are not currently available, although I would like to provide packages for Ubuntu, Linux Mint and Gentoo at some point.

To run on linux, you'll have to have a Python 3.6 environment set up. How to do this will depend on your distribution, but there's a good chance that if it is not installed already, your package manager will be able to install it for you.

I'd recommend using a virtual environment so you don't clutter up the system python, but if you're willing to risk it, the virtualenv step is optional:

virtualenv /some/path/to/your/virtualenv
source /some/path/to/your/virtualenv/bin/activate

Then, install with:

pip install omnivore

On some distributions, you will need development libraries to install wxPython 4 because pip needs to compile it from source. On ubuntu this is:

sudo apt-get install libgstreamer1.0-dev libgtk-3-dev libwebkit2gtk-4.0-dev

Linux Mint does not have a C++ compiler installed by default, so additional packages are needed:

sudo apt install g++ python3-dev

And on Gentoo this is:

emerge -av net-libs/webkit-gtk

Installing From Source

If you're interested in hacking on the code or making bug fixes or improvements, you can install and run the source distribution.


  • Python 3.6 and above, capable of building C extensions
  • git

Note: Python 2 is not supported.

Your version of python must be able to build C extensions, which should be automatic in most linux and on OS X. You may have to install the python development packages on linux distributions like Ubuntu or Linux Mint.

Windows doesn't come with a C compiler, but happily, Microsoft provides a cut-down version of their Visual Studio compiler just for compiling Python extensions! Download and install it from here.

Virtualenv Setup

I'd recommend using a different virtualenv than the one used above because it's possible that python packages that the git source depends on may be at different versions than the current published version:

python -m venv /some/path/to/your/development/virtualenv
source /some/path/to/your/development/virtualenv/bin/activate

Get the source from cloning it from github:

$ git clone
$ cd omnivore
$ git submodule init
$ git submodule update
$ python build_ext --inplace

Running the Program

Once the C modules are built (the Enthought library requires a C module and Omnivore has those several Cython modules for graphic speedups), you can run the program from the main source directory using:

$ python


Graphics Speedups

The Cython extension is used to speed up some of the time-critical code (like repainting all the character graphics), but it is only required if you were going to debug or recompile those specific .pyx files. Cython is not needed for hacking on the python code.

Should you change a cython file (e.g. omnivore/arch/antic_speedups.pyx), use the command python to turn that into a C extension, then use python build_ext --inplace to regenerate the dynamic libraries.


Omnivore will be able to be extended using plugins based on the Enthought Framework which are discovered automatically at runtime using setuptools plugins.

The plugin architecture is documented by Enthought, but is not terribly easy to understand. I intend to produce some sample plugins to provide some examples in case others would like to provide more functionality to Omnivore.


In addition to the Omnivore program itself, this module can be used in other projects. For example, Omnivore supplies a python front-end to the cross assembler ATasm, meaning you can compile 6502 code right from your python program.

ATasm Example

From the ATasm readme:

ATasm is a 6502 command-line cross-assembler that is compatible with the
original Mac/65 macroassembler released by OSS software.  Code
development can now be performed using "modern" editors and compiles
with lightning speed.

A simple example:

#!/usr/bin/env python

from omnivore.assembler import find_assembler

assembler_cls = find_assembler("atasm")
assembler = assembler_cls()

asm = assembler.assemble("libatasm/atasm/tests/works.m65")

if asm:

Because omnivore provides a very thin wrapper around ATasm (and very little ATasm code was changed) it needs to creates files to do its work. These files will be created in the same directory as the source file, so the directory must be writeable.

The segments attribute will contain a list of 3-tuples, each tuple being the start address, the end address, and the bytes for each segment of the assembly. A segment is defined as a contiguous sequence of bytes. If there is change of origin, a new segment will be created.


No warranty is expressed or implied. Do not taunt Happy Fun Ball.


Omnivore, the 8-bit binary editor, emulator, and debugger Copyright (c) 2014-2021 Rob McMullen (

This Source Code Form is subject to the terms of the Mozilla Public License, v. 2.0. If a copy of the MPL was not distributed with this file, You can obtain one at

Other Licenses

  • dirent.h is Copyright (c) 2015 Toni Rönkkö. It is Windows compatibility code used in libatari800 and licensed under the MIT license which is MPL compatible. See the file LICENSE.MIT in the source distribution.
  • atari800 is Copyright (c) 1995-1998 David Firth and Copyright (c) 1998-2018 Atari800 development team, licensed under the GNU GPL which is MPL compatible.
  • 6502-emu is Copyright (c) 2017 David Buchanan and licensed under the MIT license. See the file LICENSE.MIT in the source distribution.
  • udis is Copyright (c) Jeff Tranter. It is the basis for libudis, my fast C disassembler. It is licensed under the Apache 2.0 license. See the file LICENSE.apache in the source distribution.
  • ATasm is Copyright (c) 1998-2014 Mark Schmelzenbach and licensed under the GNU GPL which is MPL compatible.
  • tinycthread is Copyright (c) 2012 Marcus Geelnard and Copyright (c) 2013-2016 Evan Nemerson, licensed under the zlib/libpng license. See the file LICENSE.tinycthread in the source distribution.