I am trying to understand the trade-offs between scalar and vector machines, the threshold of complexity/transistor count/performance at which vector machines started to make sense.
As data points, the Cray-1 was a vector machine, but the earlier CDC 6600 was not, and as far as I can tell, the CDC 7600 was not either.
So, defining a vector supercomputer as a machine on which you can add or multiply two vectors of floating-point numbers with a single instruction, and stipulating that each vector must be at least as large as two double precision numbers,
What was the first vector supercomputer?