Jerome Fine replies: As usual, you are correct. I suspect that my error would have been noted as soon as the attempt to actually plug the 40 pin cable into the 34 pin header of the RX50. As for the lack of a twist, I seem to remember that the twist was only after the first connection, i.e. on the second connection. Since there is only a single connection to the RX50, if I am correct, the twist would not affect anything. And finally, on the PC I use, there are indeed two floppy drives with A: being a 3 1/2" drive with a header and B: being a 5 1/4" drive with an edge connector - although the actual cable in question has 5 connectors: (a) a header at one end for the motherboard (b),(C) both an edge connector and header in front of the "twist" for the first drive with only the header being used for the A: drive (d),(e) both an edge connector and header after the "twist" for the second drive with only the edge connector being used for the B: drive I beg forgiveness for using a PC, but I really use the PC to run RT-11! And the B: floppy drive is used as an RX50 - well a single RX50. This use of old RT-11 software is getting weird when I think of the first PDP-11/05 I used 30 years ago to run V2.0B RT-11. Sincerely yours, Jerome Fine -- If you attempted to send a reply and the original e-mail address has been discontinued due a high volume of junk e-mail, then the semi-permanent e-mail address can be obtained by replacing the four characters preceding the 'at' with the four digits of the current year.