Presumably in that kind of machine, a "register" explicitly means "the link between one execution unit and another" and an "instruction" configures how a specif

Presumably in that kind of machine, a "register" explicitly means "the link between one execution unit and another" and an "instruction" configures how a specific unit is linked to others. There are no "names of registers," only "names of execution units". 1. When you program this machine, you have to compute the schedule at compile-time. Exactly when and how long do you keep certain units linked? 2. You probably have a worse routing problem? - if you want to perform arbitrary instructions in a chain, all execution units need point-to-point physical wires to carry data to/from all the other units that they might need data from (and most of them will necessarily be unused?) Instead of having a massively distributed network of execution units, it's probably more efficient to have "virtual" links between units: which you implement as shared access to a centralized memory (a "register file").