idea for a universal disk interface

[Fred Cisin]

On Wed, 13 Apr 2022, Paul Koning wrote:
> Indeed.  Though even that is hard for the more exotic formats, if 
> original controllers are unavailable.  How would you read, for example, 
> an IBM 1620 or CDC 6600 disk pack, given that the machine is hard to 
> find and those that exists may not have the right controllers?  But both 
> are certainly doable with a "generic" track extractor engine.  Turning 
> track waveforms into data then becomes a matter of reverse engineering 
> the encoding and constructing the software to do that.  This may be 
> hard, or not so hard.  For example, if you wanted to do this for a CDC 
> 844 disk pack (RP04/06 lookalike but with 322 12-bit word sectors) you'd 
> get a lot of help from the fact that the source code of the disk 
> controller firmware, and the manual describing it, have been preserved.
>
> Then as you said the real goal is to recover files, which means also 
> having to reverse engineer the file system.  That too may be documented 
> adequately (it is in the 6600 case, for example) or not so much (does 
> such documentation, or the OS source code, exists for the 1620 disk 
> operating system?).


Some projects are well beyond the reach of even the most insane of us.

I don't think that any of us here today have the ability to build a 
replacement drive from scratch.  Even with full access to the original 
construction documents.

Now, if we had NSA level of facilities, . . .
It certainly seems that it would be THEORETICALLY POSSIBLE, with an 
extreme budget, to build a high resolution device similar to the 3M 
Magnetic Tape viewer, . . . 
https://blog.adafruit.com/2020/03/01/the-magnetic-tape-viewer-see-the-sound-on-a-tape/
. . . and use it to make optical imaging of the magnetic recording, 
followed by non-trivial analysis to decode that into track images, and 
then ultimately deciphering the encoding, track structure, and then 
directory structure, . . .
It is certainly not feasible now, but someday, . . .



I have a RAMAC platter!
It is seriously FAR too damaged to consider restoring it to usable form.
I was also told that it was extensively "degaussed" when it was 
discarded (possibly by Zellerbach Paper).
100 cylinders (with 100 heads in assembled structure), holding 5 million 6 
bit characters, or a bit less than 100K per platter.
So, I am making a 24" patio table out of it (under 3/8" tempered glass).
http://www.ed-thelen.org/RAMAC/RAMAC_Plaque_v40.pdf

When Khrshchev was denied access to go to Disneyland, they took him on a 
tour of the RAMAC factory, "to make up for it".   _I_ would rather be at 
the RAMAC factory in 1959 than at Disneyland, but the Khrushchevs were 
disappointed.


--
Grumpy Ol' Fred     		cisin at xenosoft.com