Re: Need an 8280 formatted 8" disk

From: Rob Clarke <>
Date: Mon, 13 Feb 2017 19:03:14 +0100
Message-ID: <>
> 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 19:00:02

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