Writing 8" floppies with SuperCard Pro
Jerome H. Fine
jhfinedp3k at compsys.to
Wed Aug 12 13:12:58 CDT 2015
I forgot to mention one item. Since I had VERY few Double Sided
media with the index hole offset that extra 1/2" from the Single Sided
index hole - and I have many RX02 compatible floppy media which
are Single Sided with the index hole in the wrong place for being a
Double Sided media - I added a DPDT switch to the sense circuit
of the DSD 880/30 drive. In the normal position, the Single Sided
floppy media are detected as Single Sided floppy media. In the
opposite position, a Single Sided floppy media is detected as Double
Sided and the DSD 880/30 is then able to read / write both sides
of the floppy media. Since the DSD 880/30 is also able to perform
a LLF (Low Level Format), I am able to use all of the RX02 media
as Double Sided WITHOUT the inconvenience of having to punch
the extra index hole.
>Jerome H. Fine wrote:
> >Josh Dersch wrote:
>> Here at the museum I'm evaluating the use of a SuperCard Pro
>> (http://www.cbmstuff.com/proddetail.php?prod=SCP) to archive and
>> duplicate 8" floppies from various machines. It's not technically
>> supported (the manual states that it *should* work but has not been
>> tested, etc.) The disks I'm reading are nothing exotic (They're
>> standard double-density, double-sided disks with an IBM format -- I
>> could use a PC and ImageDisk to do the job, but the SuperCard is very
>> convenient, in theory...)
>> Thus far I've been successful in creating images of floppies, but
>> less successful in writing them back out. Thus far I've tried a pair
>> of Shugart 851s and a Qume QumeTrack 842. I'm using a DBit FDADAP
>> (http://www.dbit.com/fdadap.html) to deal with cabling and the TG43
>> signals. (And the 851s are jumpered properly for the TG43 signal, as
>> far as I can tell). I've also tried a variety of media (Verbatim,
>> Maxell) with the same results (though the position of the bad data
>> varies from attempt to attempt).
>> The issue is that upon reading back a disk that has been written via
>> the SuperCard, data is fine up until about cylinder 60, at which
>> point bad sectors start appearing more and more frequently (though
>> most of the data is still OK). I tried disabling TG43 just to see if
>> it made a difference, and it does - with TG43 disabled sectors
>> written past cylinder 43 read back as garbage.
>> I'm running short of ideas. Anyone else have any experience with
>> this combo? Any suggestions on troubleshooting tips?
> I doubt that this suggestion will help, but it might be
> useful for what are called RX03 compatible media.
> The RX02 drive from DEC was emulated in hardware
> by DSD (Data Systems Design). DSD Produced a
> drive which was named the DSD 880/30 which consisted
> of 3 * RL02 internal drives and a single floppy drive which
> could read IBM Single Density and DEC Double Density
> floppy media. The DEC names for those two floppy media
> were RX01 and RX02. The actual DEC RX02 drive was
> able to read in both Single Density and Double density modes.
> In the case of the DEC RX01 and DEC RX02 drives, they
> were both Single Sided. Further DEC did at one point intend
> to support a Double Sided drive which I understand was to
> be called the DEC RX03, but it was never released that I
> ever heard about. The software support was specifically
> included in V04.00 of RT-11 in the file DY.MAC, but was
> probably never tested since the code was incorrect. By
> V05.00 of RT-11, DY.MAC no longer contained the extra
> code to support Double Sided media.
> DSD extended the support and the DSD 880/30 contained
> an RX03 compatible drive which could read Double Density
> Double Sided media. What I don't know is IF the physical
> characteristics of the Double Density media which DEC and
> DSD supported are identical to the Double Density physical
> characteristics of the floppy media to which you refer as having
> "an IBM format" since I have never encountered any floppy
> media from IBM other than Single Sided / Single Density.
> To make matters simple IF the floppy media which you have
> are compatible with DEC RX02 Double Density format, then
> with the DSD RX03 floppy drive, I extended the DY.MAC
> file for RT-11 and it now supports reading a Double Sided /
> Double Density floppy mounted in a DSD RX03 drive. If
> you can manage to locate a DSD 880/30 and controller to
> run on a DEC PDP-11/73 with RT-11, then I can make the
> DYX.SYS device driver available. To first make sure that
> everything will work with the DSD 880/30, you can test your
> floppy to see if a DEC RX02 can at least read the first side of
> your floppy.
> Please let me know if you know the answer to if your Double
> Sided / Double Density floppy media are DEC RX02 compatible
> on at least the first side. If that is true, then the DSD 880/30
> drive will probably be able to read both sides very easily.
> If you have any questions, please ask.
> Jerome Fine
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