How to read recalcitrant floppies?

From: Ethan Dicks <ethan_dicks_at_yahoo.com>
Date: Mon Apr 19 10:26:36 1999

--- John Foust <jfoust_at_threedee.com> wrote:
> At 11:52 AM 4/17/99 -0700, Ethan Dicks wrote:
> >I am attempting to back up some floppies from a project I did a few years
> >ago.
>
> Try several different drives on different machines.

Done. Used a *new* drive in case my regular drive was dirty, too.

> Try reading them on other types of machines, like Macs or Amigas with
> proper DOS-reading abilities.

That was my next trick. The Amiga reads disks strangely (one track at a
time in MFM mode, then converts MFM to binary data by using a portion
of the graphics hardware to run a miniterm transformation on the buffer;
it uses a 4096-bit shift register in the sound chip to slurp up the track
in the first place, the major reason why C= sold 1/2-speed high-density
drives that work on Amigas going back to 1985 with no hardware modifications).

I'll try the Amiga route this week.

> Another good trick is to hold the disk between your thumb and first finger, >
then whack each edge on the table-top.

I've done that. My question is, how does that work?
 
> Also, get out the can of compressed air to clean out each drive before you
> try this, and open the shutter on each disk and blow them out, too.

I typically blow gently on the open shutter, being *very* careful to keep
the airstream dry. I am not blessed with a collection of canned air.

Thanks for the tips,

-ethan

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Received on Mon Apr 19 1999 - 10:26:36 BST

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