Creating 5.25" floppies

drlegendre . drlegendre at
Mon Aug 17 20:42:11 CDT 2015

Terry & all,

To be clear - SD on a "360K" floppy is 180K? Yes?

Also, what's meant by a "1a"? My mainboard is marked "Rev A" but the
machine was made in late 1982, so I have a hard time believing it's really
the original Ver. A that shipped in the very early units. The board & parts
compliment endured multiple revisions, I'd expect a late-82 board to be in
the Ver. F range - particularly with a 1.4 ROM.

Did they pull first-rev boards and stuff them in the new cases, with latest
ROMs and the DD daughtercard?

On Mon, Aug 17, 2015 at 7:55 PM, Terry Stewart <terry at>

> >I've got this hazy memory saying that the boot area (or possibly just the
> first track?) of the 'DD' CP/M disk might still be FM, though, even
> >though the rest of the disk isn't, and so it needs a FM-capable controller
> to write out an image. Maybe I'm mixing that up with a different system,
> though..
> I think you might be.  I have an Osborne 1a with the DD modification.  I
> can make good Osborne boot disks for it in a 360k floppy drive using
> Imagedisk on my Pentium II.  The latter can't write single density at all
> though.
> Tez

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