Yeah the 5 dimensional torus network used at MIRA is just too cool not to bring up here. Modern supercomputers are increasingly become less and less discrete.
Think of it as loops in 5 dimensions (x,y,z,a,b). I believe each node connects to 10 different neighboring nodes (2 in each of 5 dimensions), although I could be mistaken on that. You can actually tune which direction you prefer the nodes to communicate over by passing certain flags when you submit a job.
Oh so it's actually a 5D grid that wraps around. Confusingly that would make the standard torus a 2D torus, they're referring to the surface dimension instead of the euclidean space it can be embedded into.
If so, that could be interpreted as simply a 4D square grid which wraps around the edges, right? (just as a 3D torus is a 2D grid which wraps)