[cctalk] Re: Computer of Thesus (was: Re: Re: Computer Museum uses GreaseWeazle to help exonerate Maryland Man)

[Chris via cctalk]

 




On Monday, January 23, 2023, 09:58:07 PM EST, Fred Cisin via cctalk 
<cctalk@classiccmp.org> wrote:

sorry, never had one.

Chuck might know the cookie coercivity specs!

8" and 5.25" were 300 Oersted
5.25" HD was 600 Oersted
I think that 720K 3.5" was about 600 Oersted
and 1.4M was about 720-750, being close enough that that was why you could
sometimes get away with using a 720K disk as a 1.4M

https://en.wikipedia.org/wiki/Disk_density
has a chart, but not sure if all of the sources are reliable
and does not include 2.5"

C: Remember though they are 2" disks. And shootimg from the hip, if coercivity 
wasn't on spec, would a) would that pose a threat to the disk dribe's 
circuitry. And b) could the circuit be tweaked to work with what's there. 

I'm not sure how this could be worked out, but it seems to me there could be a 
way to modify a drive so that it could measure a disk's coercivity.

There was that scene in the Jackal where a hacker woman claimed she could read 
a card's magnetic strip with a disk drive. I guess it's possible the more I 
think about it.