On 4/22/24 14:04, Paul Koning wrote: > I never had my hands on a 6600, only a 6400 which is a single unit machine. > So I had to do some thinking to understand why someone would do a register > transfer with L (shift operation) rather than B (boolean operation) when I > first saw that in my code reading. The answer is that both instructions take > 300 ns, but they are in different functional units on the 6600 so they can > start 100 ns apart.
Jack Neuhaus taught the timing course at SVLOPS, at least to the SSD crowd. It got to be fun after awhile. We tried to do the same for the STAR, but the timing was pretty complex and not a good subject for pencil-and-paper work. There, the biggest performance gains there came from vectorization. Of course, if you had ECS, large block memory moves were easy. Lower CYBER (e.g. 73) with CMU might have also benefited from its use; I don't recall if it was used for storage move early on. I do recall that the standard test for CMU presence packing a jump in the lower 30 bits of a ginned-up CMU instruction word was broken by the Cyber 170. --Chuck
