Tony Duell ard at
Thu Aug 2 13:54:44 CDT 2007

> Hi Tony,
> Thanks for the reply.
> The drive is a Micropolis 1303, and I think it has
> failed. The
> drive does spin down after a minute or so.

You know, it's really hard debuggin a machine when you're not told all 
the symptoms :-)

More seriously, this does sound like the standard Micropolis 1300-series 
problem, when that rubber bumper goes sticky and prevents head movelemt. 
The bad news is that all Micropolis 1300s (and their ESDI equivalent?) 
suffer from it, or at least if they don't they will soon.

Finding a replacement 1300-seires is probably not the wisest thing to do, 

I've never tried it, but I have heard that people have had some success 
in openign up the HDA *yes, outside a clean room), removing the bumper, 
shutting the whole thing up and using the drive as normal. How long it'll 
keep working is anohter matter.

> I noticed the PERQ manuals do state that the hard disk
> must
> be able to perform a "locate disk heads" operation,
> even
> for a floppy boot - which I assume means find track 0.

I beleive the hard disk must og 'Ready' Quite what that means I will have 
to check -- the boot ROMs check for a particular state in one bit of a 
particluar port. I candig out the EIO and DIB schematics to find out just 
waht that means if you like.

> Hence
> I'm unable to boot from floppy.
> I will check the signal levels just to be sure.
> Wondering where to go from here. I'm guessing I could
> buy a 
> replacement 1303 drive - but they are not cheap (hence
> my
> other posting) just to try and see.

Any reason not tu use some other ST412-interfaced drive? The PERQ _can_ 
use it. 


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