The RX50 floppy is 1 sided, 80 track, double density, 10 sectors per track. A program by John Wilson, wilson@dbit.com, PUTR, will format and transfer data to an RX50 formated disk. It can transfer a file into an OS/8, RT-11, or RSTS/E file system. It is an MS-DOS only program. An RX50 floppy can be formatted in a Linux machine with a 5.25" AT floppy drive. The mini-floppy disk should be SSQD, but quality DSDD work quite well. The disk must not be a DSHD (PC-AT disk). The drive parameters must be set: setfdprm -p /dev/fd1 800 10 1 80 0 0x14 0x01 0xDF 0x18 or the following can be added to /etc/fdprm # DEC formats # size sec/t hds trk stre gap rate spec1 fmt_gap rx50 800 10 1 80 0 0x14 0x01 0xDF 0x18 and then the parameters selected by setfdprm -p /dev/fd1 rx50 and then formatted with fdformat /dev/fd1 A disk formatted by PUTR was completely read in a Linux machine using dd. It ready very slowly. I believe that this may be due to the interleave that was used. A disk formatted by Linux fdformat was much faster for dd. Both INITIALIZED in RT-11 in about the same time. Chuck Dickman, chuck@chdickman.com 7/30/2000 Updated - After 7 years of mis-information, corrected format parameters. Chuck Dickman, chd@chdickman.com 5/13/2007