I'll have to answer some other questions later, . . .
Diskettes:
For writing 10K/180K/320K/360K disks, use THOSE, never 1.2M dikettes!
"360K" diskettes are 300 Oersted; 1.2M are 600 Oersted.
The 1.2M/600-Oersted dikettes use a reduced write current (pin6? of the
interface)
Twiggy disks, and Amlyn cartridge (5 disks in a jukebox holder) were 600
Oersted.
If you try to use 1.2M diskettes for the lower density, it might seem to
be working, but the recording doesn't last. Using Roytype (who the
college purchasing agent was sleeping with) HD disks with TRS80 gave us
disks that didn't keep their contents long enough to sneakernet to another
machine!
To tell them apart, there is usually a difference of color.
and 1.2M diskettes generally do NOT have a hub reinforcing ring (unless
somebody manually added one later)
360K diskettes generally come with a hub reinforcing ring. (except for
EARLY ones, such as Verbatim before they came out with "Datalife")
The reinforcing ring was because many early drives would occasionally
misclamp and mangle the edges of the hole; later drives, including all
1.2M were probably an improved shape of clamping cone.
In contrast, 720K/400K/800K 3.5 inch disks are 600 Oersted;
1.4M 3.5" disks are about 750 Oersted
Which is close enough that a high quality 720K disk could be used as a low
quality 1.4M, . . .
--
Grumpy Ol' Fred [email protected]
