[sebhc] Hard-sectored disks

Dave Dunfield dave06a at dunfield.com
Fri Feb 9 06:59:45 CST 2007

> >the Apple II used 16 hole hard sectored disks.  I presume it would at least 
> >be a major undertaking to get these to work on Heath hard sectored setups. 
> >At a minimum it would seem to require a rewrite of the H17 ROM.
> It did? I always thought Apple II disks were soft sector, though the recorded data format was
> unusual (not FM or MFM, but rather pulse width encoding).

The Apple-II was soft-sector, and didn't use the sector hole - that is why you could just
cut the WP notch and flip a diskette over without having to punch the index hole.

> Northstar computers used 16-hole hard sectored disks. 

No, NorthStar uses 10-sector diskettes (physically the same as H17 diskettes, although
the actual format is different)


dave06a (at)    Dave Dunfield
dunfield (dot)  Firmware development services & tools: www.dunfield.com
com             Collector of vintage computing equipment:
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