What makes a disk removabe?

How BIOS or Windows knows that a disk drive is "removable"?
Is this returned by the drive itself, or determined by the BIOS, or ACPI?

I have a weird single board PC that needs an 1.8" drive of a rare type.
So I use a regular Sandisk CF card, with a CF to IDE adapter.
The BIOS sees it as a "removable IDE drive".

When I install WinXP or 2003 on this, the setup happily formats the card
and copies all the files - though it warned that can't create partitions on
a removable disk, so I let it to format the whole card.
But when it reboots, a strange error occurs.
"invalid boot.ini ... booting from c:\windows ... ntdetect failed"
Recovery console shows that all the files are on the card, the boot.ini
looks ok.
Win7 setup does not even recognize this disk.
Linux installs on it just fine.

Can Windows be instaled on a removable drive?
Or, is there any way to tell the BIOS and Windows that the disk is NOT
removable?
Or am I barking on the wrong tree? Any ideas?

Regards,
--pa