On Tue, Jan 5, 2021, 7:20 AM Paul Koning via cctalk <[email protected]> wrote:
> > > > 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. > Reading this is true. There are several drivers for this for DOS, linux and FreeBSD (though the latter may be out of tree). Writing on PC and reading on a Rainbow is possible, but it is unreliable because the 1.2M drives aren't that good at writing lower the lower density data rates. Fun fact: the 720k 3.5" floppies can handle 10 sectors per track just fine. You can boot a Rainbow off one of these even, but I didn't keep that setup for reasons I don't recall.. Warner >
