My port of the New Typesetting System (NTS), called KeenType, whittles down the Java-based implementation to a few of Knuth's files. Namely, "plain.tex" and "hyphen.tex":
Getting familiar with the fonts required understanding the difference between font metrics (TFM files) and the fonts themselves. To make matters a little less straightforward, Knuth created a special character mapping for indexes into the fonts. It was not easy to find a font that mapped those glyphs exactly. The closest font was BaKoMa: