Jerome Fine replies: By the way, the RD53 is a Micropolis 1325 or 1335 with the R7 jumper added to the logic board. Otherwise, the DEC RQDX2 will not recognize the drive. I have never tried them on the RQDX3 without the R7 jumper, but it might be possible - probably NOT. And while there may still be rare occasions when you can actually complete the FORMAT required for an RD53, I would recommend that they be used ONLY for scratch at this point at the end of their life cycle. I suppose that there might still be the odd RD53 that is still living a good life, but most (almost all) have become so unreliable that I strongly recommend NOT using them for any files you care to see the next time you turn the computer on. 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.