Reusing old floppy *drives*

On 23/03/2010 19:19, Gene Buckle wrote: All 3.5" drives spin at 300rpm[1] and don't change the rotational speed when switching between DD and HD. 5.25" HD-capable drives sometimes do; many can run at either 300rpm or 360rpm, and sometimes that's controlled by the Density Select pin on the interface. Sometimes not, in which case the norm is to run them at 360rpm even for DD, but use 300kbps data rate for that instead of 250kbps. Otherwise, the standard is to use 250kbps at 300rpm for DD, and 500kbps at 360rpm for HD -- which is why you only get 1.2MB on a 5.25" HD disk when you get 1.44MB[2] on a 3.5" HD disk: 500kbps at 300rpm fits more sectors in. [1] Apart from early 600rpm drives, such as some Sony drives, that use twice the data rate, ie 500kbps for double-density MFM. [2] for certain ludicrously illogical definitions of MB -- Pete Peter Turnbull Network Manager University of York