> On Jan 5, 2021, at 6:56 AM, Joshua Rice via cctalk <[email protected]>
> wrote:
>
> These links may help:
>
> http://decvax.50megs.com/doc/rqdx/rqdx.html
> <http://decvax.50megs.com/doc/rqdx/rqdx.html>
> ...
> There’s definitely incompatabilities between the RQDX2 and RQDX3. They
> shouldn’t be assumed to be designed or act similarly, despite their names.
> The only similarity is that the RQDX3 can read the same floppy disks as the
> RQDX2 formats.
It's surprising that the RQDX3 wasn't made format-compatible with the older
controllers.
As for floppies, the RX50 format is the same for all PDP-11/VAX systems.
Unlike hard drives, Pro floppies and RQDX3 floppies are identical. The
geometry is handled in the host for the Pro and in the controller for the RQDX
case, but it's the same geometry. And by the way, a PC floppy drive can handle
RX50 floppies without any trouble, if you set it to the correct geometry -- in
particular, you have to tell it there are 10 sectors per track rather than the
PC default of 9 sectors.
paul
