Does it support all versions of TeX?

MathMagic supports Plain TeX, LaTeX, AMS-LaTeX, and MediaWIKI TeXvc for mathematical equations and symbols.
Both Mac and Windows versions have mostly the same TeX capatiblity as they are based on the same TeX conversion engine.

MathMagic doesn’t support all the features of TeX. It does not support some features related to page layout commands or macros. Please refer to the User Guide, the section describing TeX that MathMagic supports for the detail TeX compatibility codes.
The list of MathMagic supported LaTeX symbol names are available here.

MathMagic also allows user to type in TeX expressions directly in the editor window, converting it into equation when shift-return entered.