Convex Computer the C-series vector computer, the Exemplar was a parallel-computing machine that used HP PA-7200 microprocessors, connected together using SCI. First dubbed MPP, these machines were later called SPP and Exemplar and sold under the SPP-1600 moniker. The expectation was that a software programming model for parallel computing could draw in customers. But the type of customers Convex attracted believed in Fortran and brute force rather than sophisticated technology. The operating system also had terrible performance problems which could not easily be fixed. Eventually, Convex established a working partnership with HP's hardware and software divisions. Initially it was intended that the
Lens (optics) object off the optical axis of the lens is imaged, where rays pass through the lens at an angle to the axis θ. Rays that pass through the centre of a lens of focal length "f" are focused at a point with distance from the axis. Rays passing through the outer margins of the lens are focused at different points, either further from the axis (positive coma) or closer to the axis (negative coma). In general, a bundle of parallel rays passing through the lens at a fixed distance from the centre of the lens are focused to a ring-shaped