First, opensmalltalk-vm (a.k.a. the Cog VM) is the virtual machine beneath the Cuis, Pharo and Squeak Smalltalk dialects.
Second, the core VM, which comprises the execution engine and garbage collector, and the core plugins, is developed in Smalltalk, using the VM Simulator. This repository contains the code generated by the Simulator, and the platform support code for the entire VM, its CI infrastructure and so on. The core VM should not be developed by editing the generated code. The core VM should be developed using Smalltalk. The source code repository for the VM is http://source.squeak.org/VMMaker.html.
You can find scripts to build a Smalltalk image in which to do core VM development in the image directory in this repository. You can read about the Simulator here:
Cog is an evolution of the Squeak Back-to-the-future Smalltalk virtual machine that provides a number of different Smalltalk virtual machines. The VMs are developed in Smalltalk, using all the dynamic and reflective facilities of the Squeak/Pharo Smalltalk system. As such, developing in Cog is a delight. The Smalltalk framework comprising the various Cog VMs is translated into C by its Slang component to produce VM source that is combined with platform-specific support sources and compiled via a C compiler to obtain a fast production VM. This directory tree includes the output of Slang for various configurations of "Cog VM" and the associated platform support code, plus build directories that can be used to produce production VMs.
This directory tree also includes an instance of the Smalltalk Cog development system, suitable for developing the VM in Smalltalk, and for generating new VM sources.
Last modified 25 July 2021