[sebhc] Hard-sectored disks

Dave Dunfield dave06a at dunfield.com
Fri Feb 9 07:14:33 CST 2007

> i'm not an apple expert but here's the source that says the Apple II used 16 
> "hard" sectored disks:
> http://retrotechnology.com/herbs_stuff/drive.html#facts

Wow - I'm surprised that Herb has such an error - I'll send him a note.
It's entirely possible that a disk subsystem existed for the AppleII which
used hard-sector disks, however the standard Disk-II system was
definately soft sector, and definately did not require the index hole at
all (I had a switch installed on one of my drives to allow you to defeat
the write protect notch sensor - with this I could make backups on the
back side of disks without having to physically alter them. They would
read in any normal DiskII drive like any other write protected disk).

> it also (correctly) says that Heath & Northstar used 10 sectored disks.  Of 
> course, just because it's on somebody's blog doesn't make it necessarily 
> true!...

I can confirm that NorthStar is 10 sector, as I have several NorthStar
systems and controllers. Although I don't have an H17, I did implement
the H17 disk system in my H8 simulator, and it definately has 10 sectors
as well.


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