Re: Need an 8280 formatted 8" disk

From: Mike Stein <>
Date: Mon, 13 Feb 2017 14:08:45 -0500
Message-ID: <DA36566376A6416596E75274B0602E8B@310e2>
Yes indeed, a 5.25" HD drive is more or less the same logically as an 8" drive and, properly connected and configured, the controller could probably not tell the difference; on the other hand, making the correct cables, setting the drive jumpers correctly etc. adds a few more potential problems, so I'd sure try to work with the 8" drive(s) first...

BTW, Frank:

I watched your very nice video about repairing your 3032 and am just curious: how did you hold the camera, and what software were you using to test the IEEE port?


----- Original Message ----- 
From: "Francesco Messineo" <>
To: <>
Sent: Monday, February 13, 2017 1:08 PM
Subject: Re: Need an 8280 formatted 8" disk

> Hi,
> 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.
> Frank
> 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
>>       Message was sent through the cbm-hackers mailing list
>       Message was sent through the cbm-hackers mailing list

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Received on 2017-02-13 20:00:03

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