Sorry for saying that! I too wrote my own editor in Lisp 2 years ago, and also wrote one for the Z80-based Z88, but that was too slow, although the Lisp versio

Sorry for saying that! I too wrote my own editor in Lisp 2 years ago, and also wrote one for the Z80-based Z88, but that was too slow, although the Lisp version was okay. But the Z88 (6Mhz Z80) would have required a lot of optimisation and it was my lesson about how what can seem easy requires tons of special cases. But writing an editor is a good way to learn some things about computer science.