Hi All, thanks for interacting. However, I think the solution may be different than any of us suspected. After installing Windows 7 - and having it work well - I let Windows sleep and found to my consternation that I had the same black bios screen when attempting to reboot it. So I checked the forums to see if anyone else had that problem. Lo and behold, I found a post that said Windows 7 wouldn't reboot when he had an HD attached. I took that as a clue. Here's what I wrote to him:
"Interestingly enough, I had problems with Windows 7 (as well as Windows 8) restarting with some external HDs attached - three different ones, actually. After reading your note, I wondered if the issue with the failure of Windows 7 to restart might have to do with the fact that the HDs were attached. I ejected them in OS X and then tried a reboot - Voila! There was Windows 7, all happy again.
With respect to checking to see if the HDs are boot options, OS X (I'm using 8.2) does that prior to an OS coming up. If you hold down the Alt key while Boot Camp is restarting the Windows and Mac disks come up along with the Mac Recovery partition - not the external HDs (unless, I suppose, you had an OS on them). So Boot Camp already seems to know that they're not bootable. The problem might be that Windows is trying unsuccessfully to wrest control of those HDs from the Mac OS. What about it all you techs out there? Any ideas?" ....
Now I'm tempted to re-install Windows 8 and determine whether that was the basis of the non-boot problem I experienced under 8 - rather than there being no drivers from Apple yet. However, I have a few pieces of Windows software that are not compatible with version 8, so I'm going to leave well enough alone for now. Anyone else care to try it?