Oddball floppies for trade - 8", HS (outer edge), weird cutout

Paul Berger phb.hfx at gmail.com
Sun Oct 18 17:56:50 CDT 2015

On 2015-10-18 6:46 PM, Chuck Guzis wrote:
> On 10/18/2015 01:49 PM, Eric Smith wrote:
>>> To the best of my recollection, the Minnow used disks with 8 sector
>>> holes. I don't recall the modulation scheme, but FM would be
>>> reasonable.
>> 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.
> --Chuck
Page 518 of IBM's 360 and Early 370 systems says "On Minnow, the start 
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.

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