1) The REAL Lisa used 5.25" diskettes. Why would a supposed
"history" movie ("Pirates of the Valley" had some of the
personalities right on, but a LOT (MOST?) of its history was BOGUS)
be using a much later model? Didn't the Lisa change over to 3.5" occur
AFTER the release of the Mac? (in order to push out excess inventory, by
placing the Lisa as a sub-model of the Mac)
I think that the REAL Lisa's 5.25" diskettes were 600 Oerstedt (same as,
or similar to, "1.2M"). But they had a strange jacket with TWO write
access holes, in order to make it possible for users to put thumbprints
onto the diskette whichever way they held it.
2) The AMOUNT OF DIFFERENCE in the coercivity is what matters.
"360K" diskettes were about 300 Oerstedt, "1.2M" were about 600
Oerstedt, which is so far apart that they would NOT work properly.
"720K" were about 600 Oerstedt, "1.4M" were about 750 Oerstedt, which was
close enough that you could "get away with it", if you really didn't give
a shit about the integrity of your data. You could take a high quality
"720K" and punch it to use it as a crummy "1.4M", or you could take a high
quality "1.4M" and get away with using it as a crummy "720K".
I loved the ad for one of those punches, wherein the guy siad that he had
checked WITH MICROMETERS!, and confirmed that "720K" diskette media and
"1.4M" (he called them "1.44M") were identical.
On Tue, 31 Dec 2002, Ian Primus wrote:
> I was hunting around on ebay, and I found this quite by accident.
> http://cgi.ebay.com/ws/
> eBayISAPI.dll?ViewItem&category=4610&item=2085201851 It is an
> auction for some reproduction Apple Lisa system disks. The guy
> certainly did a good job copying the labels, but I really wonder about
> the data on them - the disks he used are high density floppies. I
> always thought that if you format a high density floppy for low density
> that it will work for a while, then the data will become corrupt due to
> the different magnetic properties of the media. I know that this is
> true on 5 1/4 media, I used a high density disk in a Commodore 64 by
> mistake once, and it didn't work very well. I also remember back when
> high density 3 1/2" floppies were pretty expensive, I used to buy low
> density disks and drill holes in the other corner so I could reformat
> them for high density. It worked just fine, and those disks still work.
> Can anyone shed any light on the subject?
>
> Ian Primus
> ian_primus_at_yahoo.com
Received on Wed Jan 01 2003 - 15:27:00 GMT