Re: Extracting files off “unknown” 8 inch disks. Any thoughts…

Chuck Guzis cclist at
Thu May 4 18:50:50 CDT 2017

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.


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