One problem I haven't found a mechanical solution for yet is how one could (simply) implement a state transition table - for a specific example say you have 9 states each mapping to one of 9 other states, and many-to one mappings are possible:
(This is the 3rd of 4 transition tables for an 8-state, 4-symbol Universal Turing Machine. These transitions apply if the 3rd symbol is read from tape at the current head position - with all 4 transition tables implemented you could select between them depending on the read symbol. 9 is the halt state.)
The mechanism should remain in one state and then go to the next as indicated by the table, repeatedly. How would you mechanically implement this? A face cam with many grooves perhaps, starting and ending at different angles? https://i.imgur.com/aNPBcdh.png - while always moving a follower from the center of the wheel through the groove to its edge, with something like a https://en.wikipedia.org/wiki/Chebyshev_lambda_linkage, so the wheel stops at the next angle representing the current state?
The fact that there does not seem to exist a simple answer for even this seems to partially explain why mechanical computers were quickly given up on.
Somewhat related (different project) Understand 1,700 Mechanical Linkages with These Helpful Animations (315 points, 10 years ago, 65 comments) https://news.ycombinator.com/item?id=10067743
One problem I haven't found a mechanical solution for yet is how one could (simply) implement a state transition table - for a specific example say you have 9 states each mapping to one of 9 other states, and many-to one mappings are possible:
(This is the 3rd of 4 transition tables for an 8-state, 4-symbol Universal Turing Machine. These transitions apply if the 3rd symbol is read from tape at the current head position - with all 4 transition tables implemented you could select between them depending on the read symbol. 9 is the halt state.)The mechanism should remain in one state and then go to the next as indicated by the table, repeatedly. How would you mechanically implement this? A face cam with many grooves perhaps, starting and ending at different angles? https://i.imgur.com/aNPBcdh.png - while always moving a follower from the center of the wheel through the groove to its edge, with something like a https://en.wikipedia.org/wiki/Chebyshev_lambda_linkage, so the wheel stops at the next angle representing the current state?
The fact that there does not seem to exist a simple answer for even this seems to partially explain why mechanical computers were quickly given up on.
Can't help but to link to this research https://studios.disneyresearch.com/wp-content/uploads/2019/0...
This is above my expertise, might be a better comment for this post: https://news.ycombinator.com/item?id=43859464
Somewhat related (different project) Understand 1,700 Mechanical Linkages with These Helpful Animations (315 points, 10 years ago, 65 comments) https://news.ycombinator.com/item?id=10067743
YES! he is the OG of these animations.
There are also cool sites like https://507movements.com
In some ways we are all building from the same source material. I put as much of the historical resources into this custom research page https://mechanical-library.org/mechanical-wonderland
Your animations are great! 507Movements was the one I was thinking of, several past submissions:
2021 (159 points, 30 comments) https://news.ycombinator.com/item?id=26373539
2019 (798 points, 147 comments) https://news.ycombinator.com/item?id=19968114
2015 (291 points, 27 comments) https://news.ycombinator.com/item?id=10374436
2013 (370 points, 66 comments) https://news.ycombinator.com/item?id=6230363