Re: Need an 8280 formatted 8" disk

You might find something of interest here:
http://www.retrotechnology.com/herbs_stuff/s_drives_howto.html

----- Original Message ----- 
From: "Ethan Dicks" <ethan.dicks@gmail.com>
To: <cbm-hackers@musoftware.de>
Sent: Monday, February 13, 2017 11:33 AM
Subject: Re: Need an 8280 formatted 8" disk


> On Mon, Feb 13, 2017 at 10:54 AM, Rob Clarke <crock@clarke-family.org.uk> wrote:
>> Thanks Ethan, I have no other 8" drives other than this one, and only 2
>> disks of unknown status.
> 
> That does make it harder.
> 
>> Yes, I've considered writing such a program to step the drive etc, but as
>> the ROM of the 8280 is not documented and is AFAIK, unique in using a WD
>> FD1797B-02 controller, I simply don't know how without a large amount of
>> effort to disassemble the ROMS.
> 
> 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.
> 
>>> In case there is a problem with the heads, is the drive mech of a type
>>> that can be tested on another platform?  (Tandon TM848, for example,
>>> which the photo resembles)
> 
> I looked into ftp://www.zimmers.net/pub/cbm/schematics/drives/old/8280/index.html
> 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
> http://www.dbit.com/fdadap.html)  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.
> 
> 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.
> 
> 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.
> 
> -ethan
> 
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