Extensions
The Isforth kernel (kernel.com) is a Forth compiler. It has everything you need to create your Forth projects except for things like pictured number output, the ability to save your resultant executables etc etc.
In order to add these (and other) very useful features you will need to extend the kernel by having it compile the various extensions found in the src/ext directory. Not every extension will be useful to your application however so you may extend the IsForth kernel with a subset of these. Some extensions are absolutely required (like the one enabling comments) but others are optional.
The file src/isforth.f controls the extend operation. It includes all the extensions that have been enabled. To extend the kernel you simply make kernel.com compile this source file and the rest is handled automatically. To simplify this operation I have included a ./extend bash script in the IsForth source top level directory.