Rearrange much of the polling code so really, really *busted* NEC hardware

Rearrange much of the polling code so really, really *busted* NEC hardware
mostly works, along with various other bits of cleanup.

Please, people, if you have any choice in the matter at all, avoid NEC
IDE CD-ROM drives like the plague upon mankind they are.  Especially DO
NOT connect a NEC and another brand ATAPI drive to the same controller!