Douglas Meade wrote:

> Stan,
>
> >   IIRC, the controllers for the TK-50 and TK-70 are different. Another
> > glitch may be trying to use a TK-50 tape instead of a TK-70. Apparently,
> > the timing track is written the first time a new (blank0 tape is written
> > to, and the timing tracks are different between the TK-50 and the TK-70.
> > Comments have been made about media differences, although I've
> > demagentized a TK-50 tape (with $1.00's worth of magnets!) and written
> > to it in a TK-70 drive. This is "officially" frowned upon, and I'm not
> > counting on that tape for a backup....YMMV.....
>
> Could you describe the demagnetization process more thoroughly?  I've got
> quite a few TK50 tapes right now, but only a handful of TK70's.  The
> latter are hard to come buy.  One that I picked up still had a price
> tag on it: $29.95, marked down from $49.95!  I didn't pay that much,
> I'm happy to say.
>
> Doug

Keep in mind that sources I trust have pointed out that the media between the
tk50 and tk70 cartridges are different. The tk50 media may not work reliably
for long-term storage in a tk70 drive.
With that disclaimer out of the way: I got a stack (5) rare-earth magnets
(1.0" dia * 0.250" thick), stuck them all on my beer fridge (polarity aligned,
of course), and "wiped"  both sides (top and botom) of a tk-50 tape.
The first try of just doing the bottom didn't work too well; the second time
around, I wiped each side for about 15 seconds, and moved the tape away while
maintaining the "wiping" motion.
Just for a reference  point, two of these magnets will stick to opposite sides
of my hand; they're strong little beasties!!!

I've only tried the one tape, about a month and a half ago, so I can't comment
onany long-term readability......

Stan....