A lot of that time went into the development of not the code per se, but algorithms that newer code could reimplement. Perhaps in simpler forms on newer machine

A lot of that time went into the development of not the code per se, but algorithms that newer code could reimplement. Perhaps in simpler forms on newer machines. Conventional TeX has a hard time optimizing placement of page breaks because its data structures hold only one page at a time, and discard its contents before starting the next, due to memory limitations of computers from the 1980s. Those limits no longer apply, which could make it a lot easier to code strategies for eliminating "widows" and "orphans" -- situetions in which only one line of a paragraph is stuck at the top or bottom of a page.