Mathematica is a powerful system for doing mathematics on a computer. It has an inbuilt programming language ideal for extending its capabilities to mathematical systems like Grassmann algebra. It also has a sophisticated mathematical typesetting capability which retains its computational attributes. The Grassmann Algebra book uses both. The chapters are typeset by Mathematica in its standard notebook format, making the book interactive in its electronic version with the GrassmannAlgebra package. GrassmannAlgebra can turn an exploration requiring days by hand into one requiring just minutes of computing time.
Mathematica is available for most operating systems.
To use the GrassmannAlgebra package you will need Mathematica. If you just want to read the book, you can download it as a .pdf.
If you are interested in Mathematica check out the Wolfram Research site.