After twist is always drive A.
before twist is always drive B.

The kind of drive does not matter in terms of connector placement on the ribbon. Only the connector type.

Edit:

You can get quality premade cables that are correct, and brand new on amazon.

https://a.co/d/i8LWPTJ

wierd_w wrote on 2025-04-08, 19:09:

After twist is always drive A. before twist is always drive B. […]
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After twist is always drive A.
before twist is always drive B.

The kind of drive does not matter in terms of connector placement on the ribbon. Only the connector type.

Edit:

You can get quality premade cables that are correct, and brand new on amazon.

https://a.co/d/i8LWPTJ

The thing is that I think my board is "special". When I ordered online COM1 cable, I needed to open the connector and rewire inside it, in order to make it work. "Original" wiring didn't work (at least my serial Mouse wasn't working)

I might try with amazon. In worst case I can return it.

It cannot be 'special'. The only 'special condition' is if you have fiddled with jumpers on the drives, and most late production ones dont have jumpers to fiddle. 😁

Have you confirmed jumper settings on 5.25 drive?

On twisted cable BOTH DRIVES have to be set to
Drive '2' (assuming 1-4)

Sometimes mobos go crazy when connecting cables the wrong way. You don't know how it could affect the system. I have a mobo that is very silent about where pin 1 is for its on-board FDD and HDD connectors. If I connect the floppy cable the wrong way, the system fails to recognize all IDE and FDD drives.. even after reconnecting the proper way.

The only way to make it "wake up" is by removing all ISA and PCI cards then reseating them again...

OK, so far I managed to guess correct connectors/cable orientations, so both drives does floppy seek at the boot. System works, and no error reported.
But, the 5.25" drive works only if I select 360 kb in BIOS. With 1.2M there is error on boot. I didn't touch jumpers on the drive, and regarding the motherboard I have it for a long time and I didn't touch any jumpers there except the CPU voltage, when I wanted to use Cyrix CPU which was like 2 years ago. Nothing else

I am sure that the board have some special pinout as none of the connectors/cables worked straight away, without some modification. Maybe previous owner did, but I don't know that.

Is there a jumper for the drive to support 1.2M diskette? Or this is the drive limitation? Still need to find some diskettes so I can try it out 😀

No. It may in fact be a low density drive.

An unknown motherboard with supposedly special pinout, a mystery drive, no good cable photos... Maybe being more specific with models numbers could help eliminating some possibilities, for example to know if the drive is DD or HD.

Is it a 1.2m or 360k drive?

Easy way to tell is that 1.2 has 80 tracks, 360 has 40 tracks.

Grab my ImageDisk (look on "Daves Old Computers") all you will need
is IMD.COM - it runs fine from a floppy.

It has a test/analyse function which amonge other things will let you step
to any track ... step the drive to track 40.

If the head is 1/2 way along the open area, it's 80 tack (1.2)
if near the inside end it's 40 track (360k).

konc wrote on 2025-04-09, 11:49:

An unknown motherboard with supposedly special pinout, a mystery drive, no good cable photos... Maybe being more specific with models numbers could help eliminating some possibilities, for example to know if the drive is DD or HD.

This board was discussed in my older threads on this forum, but you haven't been part of that discussion.

My motherboard is: San Li SL-586V ([SOLVED] Troubles with Cyrix 166+)
Drive: Tandon TL65-2L

That is a 360k drive, it will not support 1.2M disks. You could have just googled the model number...

Ah great now we have something: The TM65-2L is a DD/360kb drive.

maxtherabbit wrote on 2025-04-09, 15:53:

That is a 360k drive, it will not support 1.2M disks. You could have just googled the model number...

Yes, and I did, I was just wondering if this can be somehow changed, or not. Not very familiar with this type of drives. Last time I used it was about 25 -30 years ago 😀

Thanks for help

So if it will help anyone or not this is what I did in the end:
Inverted cable connector on the board side and also on the 3.5" floppy drive side. Connector for 5.25" drive was placed on the cable (in the middle), so the little plastic notch is closest to the red (pin1) wire. It is visible on the photos above.
Not sure if this will work in the end, still need to get 5.25" diskette, but in this configuration system is reporting no errors.

Thanks again to all for help.