archiving data, was RE: Media Longitevity/Care

[Gordon JC Pearce]

Ethan Dicks wrote:

> Having said that, someday I know I'll have to face at least one round
> of this... I have several DF32 drives that I expect have seriously
> worn plating (I've only ever tested the electronics, but I _have_ spun
> the platters up and down, 20 years ago, long before I knew it could
> cause a problem).  Getting a replacement platter fashioned and turned

What about RL02s?  Are they meant to be left alone once mounted and run 
up, or can you treat them like big Zip disks?

> to suitable smoothness is completely within the realm of accessible
> tools for steam engines, etc.  It's really no worse than turning a
> brake rotor.  My only real concern is _plating_ the platter.  Setting

Turning brake discs is something I've never understood.  They're cheap. 
  They're your *brakes*.  If the disc is scored or corroded, *throw the 
pair away*.  For the amount of hassle that's involved, it's just not 
worth doing it twice. </offtopic>

> up an electroplating rig is easy enough (I copper plated a number of
> nickels and quarters as a lad ;-) presuming one can a) come up with an
> acceptable formula for the coating, and b) gain access to the various

I thought the coating was sprayed on?  Looking at the edge of an RL02, 
there are clear "dribble marks" where it's run down the side of the disk.

> soluable compounds to mix up a batch of plating solution.  Even when
> that's done, one still has to construct the timing track generator,
> but at least that's well documented, so one could build the real deal
> from old DEC bits, or one could simulate a formatter with modern
> circuitry... the timing pulses are not that bad.

I did wonder about such a thing.  I'm still trying to get my head round 
the DF32 timing for my PDP8 emulator.

Gordon.