What it was was an FPU that worked alongside the real processor, and did math functions, but at a much faster rate than the standard processor. This retained 100% compatibility but it was not an FPU as such. Software that looked for an FPU would not find one.. .unless yo uhad a real FPU in there too!
Again, this is out there, but my head is wedged where the sun dont shine and its probably not a 68K CPU but somethign else???