Radio Psychedelica

Searched 'Rod logic' and synonyms.... found a depressing lack of content. Mainly noise, a lot of references to Drexler, a couple to Fowler.
(Fowlers the 'inventor' of central heating as we know it, and also of rod logic. Circa 19th Century.)
Doesn't look like anyone has done much work on them. Beyond discussing volume versus electronics volume (a popular theme - Mickey Mouse beats Donald Duck kind of calculation), or the thermodynamic implications thereof.
Only links I could find of value were:
Clever lego work:
http://goldfish.ikaruga.co.uk/logic.html
Or academic work:
http://www.zyvex.com/nanotech/mechano.html
Everyone seems to think that RAM is the toughie for any practical implementation.

Would seem simple to adapt the gates to read and punch paper tape. I wonder how much tape my crawler could carry. Or perhaps, it should string tape from the ceiling, and crawl up and down it as it computes, like some sort of algorithmic spider.

What are the implications of a rod with adjustable studs?
(I'll avoid the joke about the stud with the adjustable rod.)