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

allison allisonportable at
Thu May 4 20:27:11 CDT 2017

On 05/04/2017 09:05 PM, Terry Stewart via cctalk wrote:
>> The 'RX02' format used by PUTR is actually IBM System 34 format,
>> since DEC's 8" DD disks use a strange combination of SD headers
>> with non-standard ID marks, and DD data fields, that can't be
>> accessed with a standard PC FDC regardless of the software used."
> Right.  It's definitely a possibility then.
PUTR can do RX01 media formats.  Since the PC cannot do the unique mixed
density format
saying RX02 is potentially inaccurate.

Reason is that RX02 is a dual density drive system .  Its also a RX02
512Kb media *or* RX01  256kb.
That meas RX02 drive can read and write RX01 media in RX01 mode and
hence system 34
compatible media.  The  RX02 had three interfaces, omnibus, qbus, unibus.

RX01 is a drive system that is older and only does the 256K system 34
aka SSSD 8".  The media
is called RX01 as well.  PCs can do this.  Neither can read RX02 media
unless reformated
to RX01 (if full, you need two to hold the data due to storage capacity
difference ) or
using Catsweasel or similar.   This subsystem had three different bus
level interfaces
Omnibus, Qbus, Unibus.

The difference between the two is the bus controller and the logic in
the drive subsystem.
Both use the same physical disk drive and on first glance look the same.


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