[Coco] 1.2 MEG DRIVES might be ot

[Phill Harvey-Smith]

Quoting Mike Pepe <lamune at doki-doki.net>:

>
>>
>> People keep saying this, but I've been using switchable 40/80 track  
>>  drives for about 20 years now and never encountered this problem :)
>>
>
> You've been very lucky, or maybe you're not doing what we think you are.
>
> If you bulk-erase the disk first, it'll probably work. If you've got
> old 40-track data and write new data over it with a double-stepping 80
> tracker, the half-width new track and the other remaining half of the
> old track will make a mess that's not readable by another 40 track-only
> drive.

Humm thinking about it, it was a switchable drive so effectivly an 80  
track even in 40 track mode (with respect to the disk head width,  
which I believe is the issue here).

> I suppose if you never interchange with real 40 track drives, it will
> probably work ok.

Well, ok this is on a PC, but wrote some data to 360K disks on a 1.2M  
drive at the weekend (transfering stuff to my IBM XT !), and that  
seemed to work fine, though the disks where initially formatted on the  
XT. One thing to note here is that the XT in question does not seem to  
have the original full height IBM drive, but has a half height TEAC  
drive, ill dig out the model no when I'm at home.

It is possible of course that later model drives have the same heads  
as 80 track drives, and so would probably have no problems exchanging  
data with them, this may be worth checking out, though alas I have no  
really old drives :)

Cheers,

Phill.


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