Memorex 102 20MB Hard disk - Found It!

[Steven Hirsch]

On Thu, 22 Apr 2010, Tony Duell wrote:

>> A quick update:  The drive spins up, comes ready and is passing the seek
>> test in Morrow's FORMATHD.COM utility.  The header read fails on all
>
> Sinc this drive has a transparent cover, I assume you can see the heads
> moving during the seek trst.

Yes, and it tries to walk off the table :-).  Serious amount of moving 
mass involved!

>> sectors and all cylinders, so something is still amiss.  I tried
>> re-writing the sector headers (if I interpret correctly, it is possible to
>> simply rewrite the headers without disturbing data in the sector proper -
>
> That is not unheard-of. Howeever,  I would be a little wary of writing to
> a drive that didn;t read correctly. If something is faulty, it's quite
> possible it's going to write somewhere it shouldn't. And since the drive
> fails on every sector, I would think the fualt is unlikely to be simply
> bad formatting data on the disk.

Ah, well.  I doubt there was anything on there of value to me.

>> a new one on me!) but that didn't help.  No error on write, but they
>> cannot be read back.
>
> What error do you get if you try to read them? Does it manage to find
> anything?

No, it fails 64 times to read every sector on every track.

>> I'll start poking around in the read logic next.  Getting closer, anyway.
>
> I've not looked at the schematics, but I guess I'd start by seeing if (a)
> it was reading anything (do you get any sensible-looking pulses at the
> read data output -- and rmemeber that in 99% of drives the pusle width is
> irrelevant, it's set by a monostable on the logic board, it's the pulse
> spacing that defines the data), and (b) is it selecting one (and only
> one) head

Yes, I'm planning to poke through it with a scope tomorrow.

Steve


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