Only Windows 2000 setup had any trouble seeing the HDDs connected to that Promise card. Everything was fine in every other scenario: normally-operating Windows, Windows XP setup, etc.).
And what I was doing *used* to work; I had not changed any hardware.
So I knew it wasn't a hardware problem; there is nothing wrong with the card, cable, drivers, or the hard drive. I knew it had to be software, specifically something about the installation of the drivers for that card.
There were two crucial pieces of information: the first came from a Microsoft guy I ran into on one of the forums. He pointed me to a Knowledge Base article:
http://support.microsoft.com/?id=314859
It talks about XP, but apparently the same is true with 2K:
If you use F6 to attempt to install a driver that matches (has the same Plug and Play Identifier as) one that Windows already has, the Setup program IGNORES the driver you are trying to install. And no message is displayed telling you it did that (grrr).
So Windows setup, for some reason, (mistakenly) thinks it already has an appropriate driver for that controller card.
I blamed XP because the problem arose when I installed XP.
The F6 trick was not needed during XP installation, apparently because the XP CD contains a driver for the card, whereas the Windows 2000 CD does not.
When I installed XP, that new driver must have been "remembered" somewhere, so that when I tried to do the F6 thing during re-install of 2K, the above "ignore" scenario happened.
But ..... where is it "remembered"? The answer to that question is the other crucial piece of information.
When I changed HDDs, the problem went away. This made me suspect that the place where the driver was "remembered" was on the HDD, as crazy as that sounds. This makes no sense, because I used drives that had been zeroed out. Besides, at that point in the install, the HDD hasn't even been accessed yet. But I had no better ideas. I just kept asking around, because I knew there were some facts I was missing.
Last week I ran across a very good technical info website by a guy named Chris Quirke. I tracked down his email address and asked him the above question, and he immediately came forth with the magic acronym:
E S C D !!!!
(Extended System Configuration Data).
Plug and Play configures the hardware in the machine (assigns IRQs, DMA channels, I/O ports, etc.), and saves that configuration in the ESCD, which is a file in non-volatile RAM in the system BIOS. On subsequent boots, as long as the hardware doesn't change, the system just reads that file and doesn't have to repeat the assignment process.
Apparently when XP was installed, the Promise card's ESCD info was updated to point to XP's new driver. Then when I wiped out XP (and presumably the driver with it), that left the ESCD pointing to la-la land.
So Chris just said to go into the BIOS setup and clear out the ESCD, which forced Plug and Play to repeat its assignment process. Problem went away, end of story.
I think I even figured out why it appeared that the problem was hard-drive-specific. The first time I switched the hard drive, the one I put in was slightly smaller than the one I took out. Perhaps the different disk geometry caused the ESCD to refresh, making the problem go away for the moment. But then I repeated the sequence of steps (introducing XP) on that drive, which reproduced the problem, and then every disk I put in since then has been just like one of those two previous ones.)
Thanks again for all your time and attention,
Ted