So you plugged a floppy into the B drive connector and it didn't work as A drive? I'm amazed.

The drives are swapped!

Clearly you didn't understand what was going on in the photo. (Sarcasm isn't necessary). The floppy drive is plugged into the B position but set up in BIOS as A drive. For reasons I cannot work out the positions on the lead are reversed.

Well look through setup, there's probably a "floppy swap = enable" or "A/B swap" setting.... or it's hidden in a boot order config option where it's B: A: C: CDROM or something.

A: drive usually has the cable twisted, while B: drive hast it straight.
On your picture the drive is connected as B:, if there is no second twist next to the mobo connector.

Regarding the floppy swap comment, the CMOS was cleared and the battery removed so I fail to understand why the default position would be as described in my initial post (i.e. B: swapped with A:) Secondly there is no floppy swap option on what is a Compaq propriety BIOS unless there is a hidden menu and to be honest it does not make any sense. With regard to the floppy cable it is a standard cable with the twist in the correct place for A drive. I have used several cables and several drives but the result is always the same. it just appears on this particular board the positions appear, on the face of it, to be reversed. It all works fine and I can plug in two floppy drives it all works. What I am trying to do is to understand why I have this enigma. I have been building PCs of all types for 28 years and I have never come across this.

Well I didn't think this happened on prebuilt machines until into the 2000s when floppy drive was in full phase out, but looks like they intended it to be used single drive with a straight through cable... https://www.teamspares.com/compaq-166838-001- … data-cable.html

Thanks. That is the conclusion I came to. Then just now I had a look on Youtube and there is a video of someone with this PC and guess what? A single straight through floppy cable with no twist. Mystery solved. I'm glad because I thought I was going mad 😀

Dreamsurfer wrote on 2024-03-20, 18:50:

Having spent some time trying to work out the problem I decided to fit two floppy drives to the lead and set them both up. Both drives were recognised and worked flawlessly.

That is quite interesting , didnt compaq design their own boards?

I know the intel design and built BX boards I have only support one floppy unless they are server boards.

Yes the straight floppy cable is a common thing on certain Compaq boards, and they only support a 1.44mb drive iirc. The EP 440BX boards are like that.
Mine has number tag SP166813-001 (board # 009637-001) and is running a P3-500...