IBM 5150 PC Tandon TM100 drive select jumpers!

I am very confused. If I have a single floppy drive in my machine then are the following correct?

The ribbon cable connector that plugs into the drive is after the twist.

The drive has the resistor array plugged in to terminate it as it is currently furthest away from the controller.

Since the drive is DS0 it should be jumpered between pins 2 and 15 That is the second row?

Now this won't work, but if I jumper the pins between the third row 3 and 14 DS1 then at least the motor spins and the drive light comes on -not able to read any of my disks, probably formatted wrong.


If I were to have two drives then the second "B:" drive goes before the twist and it does not have the termination and the jumper should then be the third row? i.e. DS1 for the second drive and the A drive at the end of the cable is DS0, the second row?.

It's the jumpering that has me confused.



In this diagram I am assuming that in the two drive model the first drive is B and the second drive is A

The jumpers should not change. That was the whole point of the twist: to switch the drive settings without moving any jumpers. IIRC, both drives should be set for DS1.

https://www.minuszerodegrees.net/5150_5160/floppy_diskette/5150_5160_floppy_drive_cabling.jpg shows how it works.

What submodel of the Tandon TM100 is it? Just to confirm that it is a standard 40 track drive.

Ahh got it. Thanks. Now it makes sense.

Here is a good Photo of the crossover cable that prevents users of being confused.
Those IBM folks sure cleared all the confusion by doing their part.

Notice that Pin 10 & Pin 16 are now Motor ON.


Larry