>> microcode for the Perkin-Elmer 3220 was fun and useful as well. > > that's interesting. i found this paper and am studying it. are there > obvious advantages?
I think there were quite a few independent projects at different places adding special-purpose instructions to accelerate particular algorithms. Improving on the original P-E (Interdata?) microcode wasn't hard. For example the base instruction set had instructions for inserting/deleting elements in a doubly-linked list, which were actually slower to execute than just doing the equivalent sequence of loads & stores.
