Not sure what board we're talking about, but you can disabled floppy drives in the BIOS, incl. the floppy drive controller. The latter can be disabled and you can still configure floppy drives - don't ask me why. First thing I do on boards that will not get one. So check the bios settings again for anything obvious.
From my memory, if you insert the floppy cable the wrong way, the floppy drive LED is ON all the time and it doesn't work.

Normally, if the bios floppy is enabled, the OS should see it. Even if there is no physical drive attached.

A floppy drive plugged into power only will not show any signs of life.
At the moment, I suspect the problem lies with configuration or cabling, not the drives.

tehsiggi, you nailed it! drive a was assigned in the bios, but the floppy controller was disabled. the drive shows absolutely no signs of life until you actually perform a read/write access on a floppy. somehow i remembered it being more visceral.

Does the cable have a "twist" near one end? (see attached pic)

If not, the drive will not work as A:

When IBM designed the PC, they didn't think users were smart enough to change drive jumpers, and didn't want their dealers to have to carry two different drives (A: and B:)
So they came up which this twisted cable which passed strait through to drive B: (is there were a drive B: connector in the pic, it would be just BEFORE the twist one the long end of the cable side.
The twist moves some signals so that the drive A: select appears in the drive B: position at the end of the cable (After the twist)

1PC                                                                                      DriveB:   DriveA:
2||-----------------------------------||------||
3||-----------------------------------||\~~~~/||
4||-----------------------------------||/~~~~\||
5||-----------------------------------||------||
6||-----------------------------------||------||
7||-----------------------------------||------||

This means BOTH drives on the PC have to be jumpered as the second drive (1 if 0,1,2,3 or 2 if 1,2,3,4)

If you don't have the twist, your drive will appear as drive B: on the PC

Note that some mainboards don't even support drive B:

If you are lucky your BIOS might have a "swap" floppy drive option, which will let you use a drive (jumpered as 2nd drive)
on an untwisted cable as drive A:

Try disabling drive A: (set to NONE) in BIOS and set up for drive B: - depending on BIOS it might "test" it at startup which would cause brief activity.

If you cable does have the twist - it should work "as is" check that drives are jumpered as 2nd drive.

stanwebber wrote on 2026-07-07, 17:52:

tehsiggi, you nailed it! drive a was assigned in the bios, but the floppy controller was disabled. the drive shows absolutely no signs of life until you actually perform a read/write access on a floppy. somehow i remembered it being more visceral.

If you have the ability to run DOS, you could use ImageDisk to test floppy drives - IMD accesses the drive(s) directly (not through DOS) - I normally keep the drives set to "none" on my IMD system (to avoid other stuff possibly messing with them)

But... on most more modern (that the 5150) boards, the FDC is part of a large system chip - an that portion of the chip might be disableable in BIOS (so do check that it's enabled)

stanwebber wrote on 2026-07-07, 17:52:

tehsiggi, you nailed it! drive a was assigned in the bios, but the floppy controller was disabled. the drive shows absolutely no signs of life until you actually perform a read/write access on a floppy. somehow i remembered it being more visceral.

Some boards have an option called "Boot up floppy seek" - if it's off, it's not doing anything during boot. If on, you get the usual seeking noise on POST.

the cable is round. i assume there's a twist as drive a: is configured and accessible after i enabled the fdc controller. it was just confusing without the middle connector or blocked out pins.

ah, boot up floppy seek is what i remember back in the day. yeah, i'm leaving that off.

stanwebber wrote on 2026-07-08, 13:05:

the cable is round. i assume there's a twist as drive a: is configured and accessible after i enabled the fdc controller. it was just confusing without the middle connector or blocked out pins.

ah, boot up floppy seek is what i remember back in the day. yeah, i'm leaving that off.

Glad you got it working.

Boot up floppy seek does serve a purpose on AT+ - used to detect 40 or 80 track drive.
Home head (step in till Track0)
Seek out 50 or so tracks (enough to overflow a 40-track drive)
Seek in, counting till Track0

If <40 - report drive error, if <50 - drive is 40-track (360k), if 50 - driver is 80 track (1.2m) - if >50 report drive error!

Later on when 3.5" became common (all 80 track) this wasn't as useful which is why you could turn it OFF.