Hey man.

In my situation the issue was wire 9 and wire 20 needed to be cut counting from the red stripe on the floppy cable.

In order to use the 800k drive with my 128k board.

- Inspect your floppy cable and maybe try one from another machine.

- Sometimes a bad floppy drive will screw up the disk you have been using… making you think everything is screwed...

When it was just a bad floppy drive that keeps screwing up your boot disks, making them not work even in a

good working floppy drive.

But does the internal somehow route through the 2nd filter, while the external doesn't? That seems weird.

Click to expand...

Both the internal and the external floppy ports route through both resistor networks.

Also the mouse shares some of the network on the filter right of the internal floppy port.

One of the serial ports share some of the network too, on the filter right in front of the internal floppy connector.