Jim Thompson wrote:

My first Spice machine was a 386 with 486 co-processor. Looks like
the Xeon Phi requires software specifically written for it ??

In short, yes. The Phi cores themselves are mostly x86-compatible,
but the differences are at the upper level: they are shipped as
a PCI express card with its own OS (ssh-able). At least the ones
I've seen.

OTOH, they support OpenCL wery well, so any GPU-aware program
would also run smoothly on the Phis.

Best regards, Piotr