Rotating memory data recovery

[Tom Jennings]

On Sat, 2004-09-11 at 14:42, John Lawson wrote:
> 
>    A simple method of sync would have to be worked out, but, being the 
> AnalogGeek(tm) that I am, I'd be tempted to record the bitstreams as 
> square-wave audio data to some kind of DAW software... 

I was assuming PC audio cards would not be fast enough. I am an analog
person too, but not to your extent of expertise. 

The disk has one (or a few) timing tracks. I assumed I would record the
timing track plus a data track; hence all recordings would have a
reference. A stereo sound card would do this. There's no physical index
pulse, it's derived from disk data. I haven't looked at the timing data
for over a year, I need to RTFM before I open my mouth any more.

>   if you 
> could get a 'whole drum after this pulse' (sort of like capturing one 
> video frame) sync set up, then you could record each track onto a similar 
> parallel track in the DAW.... 

1) I figured I could capture N seconds, to get N * 1/RPM copies of data,
and pick the timing::data out.

2) What's "DAW"?

>   Recording this would be fairly tedious but apart from a high-speed 
> multi-track data-logger, It would get the job done.

Another choice is to simply disable writing electrically, and use the
computer itself. The biggest worry (at this point) is head/platter
issues. THe heads contact at rest, then lift. The mechanical issues
exist no matter the data-recovery method.


>    Another thought would be to use an external audio osc and power-amp to 
> slow down the drum motor and make it easier to record the track pulses and 
> index marks...  run the motor at 10 Htz or so.


Well the problem as I see it is deterioration of the magnetic
surface/circuit, and changing motor speed won't improve that (probably).
Lost data is secondary to a lost timing track! That would be ruinous, I
have no idea how I'd re-create that. Certainly, I need a copy of that.