9 Sep
2006
9 Sep
'06
8:59 a.m.
On 9/9/2006 at 11:26 AM joseph c lang wrote:
They have a two speed spindle 360/180 rpm and use
500kbit mfm just like
8" dd disks. 2.4 meg. only works on "microcode" disks though. And they are
pretty
scarce.
This reminds me of one of the dodges offered early on in the PC to enable a
5150 or 5160 PC to handle 1.2M diskettes without swapping the controller
card--someone offered a dual-speed drive that spun at 300 and 180 RPM (not
to be confused with the 300/360 dual-speed 1.2M drives). Apparently it
worked, but I wondered how good the S/N ratio at the lower spindle speed
was. For a short time, it was either very expensive or next to impossible
to get a 1.2MB-capable controller for a 5150, since the PC/AT put the FDC
on the HDC board. The gap was quickly filled by outfits like Micro
Solutions and Sysgen (and then the Far East cloners) and the dual-speed
drives vanished.
Is the coating on the 2.4MB floppies a standard formulation? It would seem
to be a simple matter to format these things if that were true--assuming
the drive supports writing at the lower spindle speed.
Cheers,
Chuck