Reusing old floppy *drives*

On 23 Mar 2010 at 21:26, Pete Turnbull wrote: Ever use much PC98 Japanese gear? They use 3.5" HD floppies that spin at 360K, just like 5.25" HD and their 8" cousins. It makes a lot of sense--the format doesn't change, just the physical size of the medium does. You see these a lot on Japanese and Korean CNC and lab gear, as well as the veneered and generated NEC PC9801 series of personal computers. Most makes of 3.5" drives can be jumpered or switched (although it may not be documented very well) to run at 360 RPM and some--such as most USB floppies and Imation Superdrives can detect the recording density and switch automatically. Related to this, I received two floppies in for "copying" a couple of weeks ago--a 3.5" DSHD and a 32 sector 8", with the admonition that both floppies contained exactly the same information. (Hear the head scratching?). The recording method was clearly MFM, but with unique address marks and track layout. The hard-sectored 8" turned out to be a red herring--the layout of data on the track didn't follow the sectoring at all--I suspect that someone jumpered the 8" drives for HS operation so that they could use a stock of old 32-sector media. That way, you still get only one index pulse (but 32 sector pulses on a different pin). But the 3.5", while the spitting image of the 8", wasn't identical. It had been recorded at 300 RPM, so there was about 2000 bytes of information on the last half of each track that duplicated that on the first half--and, predictably, the last of the duplicated sectors was truncated at the index. Probably someone's hack. Personally, I'd rather stick with the 8" media, as it's far more robust than the 3.5" stuff. If 3.5" drives were required, I'd run them at 360 RPM. Cheers, Chuck