Re: Need an 8280 formatted 8" disk

From: Francesco Messineo <>
Date: Mon, 13 Feb 2017 19:08:25 +0100
Message-ID: <>
just a suggestion: you could adapt a 5.25" HD drive in place of the 8"
just to test the controller, afair they have the same revolution speed
and data rate.
That said, I have a couple of boxes of 8" floppies but with unknown
(to me) format and media state since I don't have any 8" drive (I
whish I had).
I could donate a floppy anyway.

On Mon, Feb 13, 2017 at 7:03 PM, Rob Clarke <> wrote:
>> I wasn't suggesting going to that point, rather a simple BASIC program
>> to do a "B-R" command for blocks on different tracks which _should_
>> cause the drive to seek, then fail as the media under the head lacked
>> the correct format to produce meaningful results.  So it _would_
>> "fail", but the head would at least move around.
> Good plan, I didn't think of that. I just tried it with B-R and the appears
> to step up and down correctly, but of course also fails with a read error.
>> I looked into
>>   It _is_ a Tandon TM-848.  That is an easy one to hook up to a
>> "modern" machine, and for reads, you wouldn't need a "TG43" signal
>> generator (though this, from John Wilson, would take care of
>> everything including 50 pin<->34 pin wiring
>>  If you did pull one of the drives
>> from the 8280, it could be hooked up to a PC and used as an 8" drive -
>> there are formatting programs, etc., out there for such use.  this
>> would only get you the IBM 250K MFM format, but that's supposed to be
>> supported on the 8280, so I _think_ one would do OPEN
>> 15,8,15,"N0:MYDISK" to not format the media, but write out a BAM and
>> directory track).  A valid but admittedly intermediate test to
>> formatting the whole thing.
> If I don't make progress in the immediate future, that could be a plan.
>> Oh... and since it's a dual drive, I'd also consider OPEN
>> 15,8,15,"N1:MYDISK,XX" and if that failed the same way, I would
>> probably proceed under the expectation that both drive mechs are
>> probably not faulty in the same way.
> Yep, I swapped the mechanisms, both exhibit same behaviour. This is why I
> initially thought the DOS board but now wonder if it's the media.
>> Sounds like you have someone to send you an 8280 disk so you may be
>> all set, but I'd be impatient enough to at least fiddle with something
>> to read blocks on different tracks just to ensure the FD1797 FDC is at
>> least nominally happy.  Of course that won't test read/write and data
>> sep circuits or the TM848 heads, but it would test everything up to
>> that point.
> And I am indeed an impatient person so will continue fiddling. I have a
> couple of spare controller IC's, and all show same behaviour, so at least
> that can be ruled out.
> cheers, Rob
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Received on 2017-02-13 19:02:10

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