[BBC-Micro] Re-using floppies

Phill Harvey-Smith afra at aurigae.demon.co.uk
Mon Mar 22 20:10:17 CDT 2010

Fred Cisin wrote:
> In addition to all that, . . .
> The coercivity (sorta like magnetic sensitivity) is WRONG.
> "720K" diskettes are 600 Oersted.
> "1.4M" diskettes are about 750 Oersted.
> It IS close (unlike 360K (300 Oersted) v 1.2M (600 Oersted)), and it WILL
> work (unlike 360K v 1.2M), but it will NOT be as reliable as using the
> correct diskette.

It would need to be for those punchout devices that where sold back in 
the early 90s to 'convert' 720K disks to 1.44MB disks by punching the 
detect hole out.

Mind in my previous job I had to take a drill to a 720K disk that a 
studenet had formatted as a 1.44MB disk on his Archemedes, oddly the PC 
could not read it. Once the hole was drilled it worked fine.

Was this just one model of Archemedes that had this 'feature' or was it 
Acorn deciding that they could ignore the standard ?



Phill Harvey-Smith, Programmer, Hardware hacker, and general eccentric !

"You can twist perceptions, but reality won't budge" -- Rush.

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