In the past I successfully low-level formatted PC-formatted ST225 using XXDP2.5 directly on PDP11/53 with RQDX3. If I remember correctly, I used ZRQCH. As I had a machine with RX33 (5"1/4), I prepared a booting image of XXDP on SIMH, transferred the image to floppy disk with vtserver, then executed the diagnostic program, inserted the right parameters, and voil?. It worked like a charm on all the ST225 I have, also on one that have a lot of defective sectors. Andrea