2.4 Megabyte Floppies

[joseph c lang]

On Saturday 09 September 2006 11:59, you wrote:
> 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

I suspect the disk coating is not the same as 1.2m disks.  The 1.2m disks 
have a high error rate when used at 2.4m. 

The coating on the 2.4 meg diskettes is darker than the 1.2 meg disks.
It also appears to have a smoother surface.  I know that doesn't prove 
the coating is different, but I think it's a pretty safe bet.

joe lang