Amlyn Minipac diskette changer

[Steven Hirsch]

On Sun, 18 Jul 2010, Steven Hirsch wrote:

>> On 17 Jul 2010 at 16:16, Steven Hirsch wrote:
>> 
>>> I pulled down a copy of their patent application for the unit and it
>>> almost looks like the Minipac diskettes have some sort of pre-written
>>> servo track.  Perhaps the unit can actually write this servo, but
>>> without documentation I'm just surmising.
>> 
>> Could be.  It sounds a bit like the Drivetec drives of the same time
>> period.  Something like (ISTR) 192 tpi, using an embedded servo,
>> making factory-formatted disks mandatory, something that probably did
>> more to kill the drive than anything else.  I've still got a couple
>> of the Kodak/Drivetecs with media from Dysan, but basically they
>> exist for the eventuality that someone, somewhere has data written on
>> one of these that they need to get at.
>
> Gets stranger as I go...  I disassembled the drive to take a short at 
> cleaning the heads.  Turns out to be "head" (singular).  If the total 
> capacity is 6MB, then they were writing 160 tracks on a single side. That's 
> pushing the envelope for mechanical alignment on a floppy and certainly 
> explains why they used servo-feedback positioning instead of blind stepping 
> like a conventional drive.  The majority of claims on the patent pertained to 
> track positioning, so this is all consistant.

<sigh>..  It appears that the OEM Amlyn diskettes are pre-formatted in 
some manner.

I found a utility (from my Vista 8" Apple subsystem) that recognized the 
data on my Amlyn drive cartridge and was able to retrieve the system 
generation and format utilities.  The latter works fine on one of the 
cartridge diskettes, so I tried it on a blank 1.2M HD floppy that was cut 
up to fit the unit.

The new disk loads properly without mechanical issues, but will not format 
or otherwise show signs of life.  I'm guessing they wanted to preserve a 
market for blank diskettes and cartridges.  Reminds me of the DEC Rainbow 
(wasn't that system deliberately crippled to prevent it from being able to 
format blank media?).

Steve



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