If it's an RX02 operating in double-density mode,
you're not going to
read the disks with any commodity floppy controller. You will, however,
get the sector ID headers.
DEC used a rather peculiar scheme where headers were
recording in
single-density (FM), but the body of the sector (the data) is recorded
in a "peculiar" MFM, that employs some pattern substitutions to avoid
conflict with similar patterns in the headers.
Thanks Chuck
Hmm...I'll do some more checking with IMD and Anadisk tonight. I haven't
looked at this disks in Anadisk yet. IMD did recognise some things...maybe
it was the Sector ID headers.
Even if I can't get anything off, I'm now very curious as to exactly what
I'm dealing with.
Terry
On Fri, May 5, 2017 at 11:50 AM, Chuck Guzis via cctalk <
cctalk at classiccmp.org> wrote:
On 05/04/2017 04:30 PM, js--- via cctalk wrote:
On 5/4/2017 6:16 PM, Terry Stewart via cctalk
wrote:
If these
are from a VAX, could they be microcode disks for a
11/780?
There was a RX01 attached via a LSI-11 as console.
And yet, if there were an RX02 somewhere on this VAX, I don't
believe you'd be able to read them at all... RX02 seeming more likely
with a VAX.
If it's an RX02 operating in double-density mode, you're not going to
read the disks with any commodity floppy controller. You will, however,
get the sector ID headers.
DEC used a rather peculiar scheme where headers were recording in
single-density (FM), but the body of the sector (the data) is recorded
in a "peculiar" MFM, that employs some pattern substitutions to avoid
conflict with similar patterns in the headers.
A catweasel will work just fine--and there's code out there to handle it.
--Chuck