Floppy disks (almost always) run on the same cable, with a twist in the cable being used to make one of the drives respond to drive b: compared to drive a: - this is why you (almost never) have to jumper a floppy drive as a: or b: ... it's the position on the cable which determines it:

Yes, there are exceptions, especially if using floppy drives not originally intended for PC use, but the above is true in 99% of cases, and it meant that manufacturers could send out their disk drives all jumpered/configured for drive a:.

megatron-uk wrote on 2025-01-10, 08:58:

Floppy disks (almost always) run on the same cable, with a twist in the cable being used to make one of the drives respond to drive b: compared to drive a: - this is why you (almost never) have to jumper a floppy drive as a: or b: ... it's the position on the cable which determines it:

The attachment VYByP.png is no longer available

Yes, there are exceptions, especially if using floppy drives not originally intended for PC use, but the above is true in 99% of cases, and it meant that manufacturers could send out their disk drives all jumpered/configured for drive a:.

Sweet, thank you! When I see the picture I do remember those cables now. 😀 Now I just gotta see if I still have one like that to try it out.

Do you also know if it's possible to run with just a B: drive, if you really wanted to?

If you want the drive to be B: just use a straight cable. A: drive requires the twist.

jmarsh wrote on 2025-01-10, 10:20:

If you want the drive to be B: just use a straight cable. A: drive requires the twist.

Got it, thanks!

The twist works together with the drives DS (drive select) Jumper wich can be set between 0 and 3.
Usually it is set to 1 , thats why you need the twist.
Setting it to 0 should eliminate the need for the twisted cable.

There were configurations with 2 devices on a single cable.
2 FDDs and a tape streamer.
No idea how these setups worked?

megatron-uk wrote on 2025-01-10, 08:58:

send out their disk drives all jumpered/configured for drive a:.

3.5" drives are configured for B: by default if I remember correctly, but the twist at the end of the cable causes that drive to be seen as A:

Errius wrote on 2025-01-10, 15:11:

megatron-uk wrote on 2025-01-10, 08:58:

send out their disk drives all jumpered/configured for drive a:.

3.5" drives are configured for B: by default if I remember correctly, but the twist at the end of the cable causes that drive to be seen as A:

I knew I'd have it the wrong way round! 😁

If you've got systems, which were mostly post-2000, that only had a single device cable, then check you can actually select a B drive in CMOS Setup, because some of them, managed to cripple things somehow so that only a single A drive works. Though how crippled is variable, sometimes they don't appear by default in DOS but windows can still pick a second drive up, or you can use it in linux. These are typically going to be P4 or AMD A64 class upwards.

BitWrangler wrote on 2025-01-10, 16:40:

If you've got systems, which were mostly post-2000, that only had a single device cable, then check you can actually select a B drive in CMOS Setup, because some of them, managed to cripple things somehow so that only a single A drive works. Though how crippled is variable, sometimes they don't appear by default in DOS but windows can still pick a second drive up, or you can use it in linux. These are typically going to be P4 or AMD A64 class upwards.

And surprisingly, you can often set the option ANYWAY with things like GSETUP.

I have a P4 era board that staunchly refuses to allow anything except 3.5" drives, and only for the A: slot.

I can forcibly set it for B, and set it to 5.25" types with gsetup, and they work just fine.