best of my recollection, the Minnow used disks with 8 sector
holes. I don't recall the modulation scheme, but FM would be
Sure, but were the holes on the outside, like the Memorex, or near
the spindle, like all later 8-inch floppy drives?
My recollection is on the outside. Makes sense, too--far easier to
get those punched accurately.
Page 518 of IBM's 360 and Early 370 systems says "On Minnow, the
fo a sector had been indicated by eight sector holes uniformly spaced
around the outer edge of the disk"
It goes on to say that when the first read/write drive was developed
(Igar) the hard sector holes where dropped in favour of more usable
surface are. I have seen the diskettes for minnow and and they where
considerably less floppy than the later diskette.
It is hardly surprising that Memorex followed this scheme in those days
they where famous poaching engineers and producing clones of IBM storage
products. I remember a customer having a Memorex disk unit on a string
of 3370s and I think you could have swapped parts between the Memorex
unit and a 3370.