Current source for RX50 media?

On 06/24/2016 09:13 PM, Fred Cisin wrote: IBM-style PCs with 1.2M drives use a 300Kbit/sec transfer rate for double-density floppies. A tool such as Dave Dunfield's IMD will work just fine. The last time I duped a bunch of RX50s, I used Verbatim "DSDD" media. Forget about searching for "96 tpi" or "100 tpi" branded floppies--all that indicates is that verification was performed as part of manufacturing QA at the indicated track density--it doesn't really have a bearing on the results. If a DSDD floppy is good at 360KB, the chances are overwhelming that it'll be fine in DSQD mode. As far as ring-less hub floppies go, those are difficult to find and probably quite old, unless they're specifically labeled (complete with little arrows) for RX50 use. Hub rings differ between brands in thickness; the "clear" type are generally thinner than the opaque (black or white) ones. As an aside, the reinforcing ring was originally introduced for early FH 5.25" drives that didn't have circuitry to sense when a disk was being inserted and activate the spindle motor. The result that a floppy could be clamped off-center and mangle the hub area and the data on the floppy itself. I remember that Dysan and Verbatim started doing this when the old un-modified Micropolis drives were in use. Initially, it started with a supplied jig and a bunch of self-stick hub rings. In a short time, the jig and rings were dropped and floppies simply came with the rings applied. As most 8" drives of the time have AC line motors that spin continuously, this mis-registration was never a problem there. When half-height DC-spindle motor 8" drives came out, the problem was already known in the industry, so 8" floppies don't have the rings. 1.2M (DSHD) floppy drives came much later, after the problem had been diagnosed and remedied, so those don't *unually* have hub rings. FWIW, Chuck