hard-sector 5 1/4 disk

From: UberTechnoid_at_home.com <(UberTechnoid_at_home.com)>
Date: Tue Oct 30 16:17:27 2001

I recall the Amiga having a high-density external disk addon that ran at
1/2 speed so Commodore wouldn't have to include a faster fdd controller
chip. The bad news. The good news is that it worked on all Amiga
machines right out of the box.

The ATR8000 and ATR8500 CP/M boxes DO for Certain use the index hole to
time the drive's rotation to determine if it is an 8" or a 5.25" mech
running. I've used a couple of 3.5" high-density drives on them and
gotten up to 1.35mb in CP/M and 1mb in Spartados. The trick is getting a
3.5" mech that has a big ol' block of jumpers on it. You can fiddle with
the jumpers and make the drive emulate a 77track 8" mech.

As for the index hole, this wasn't such a bad thing unless you wanted to
use 'flippy' disks in an ATR. Atari drives don't use the hole at all so
flipping the disk works fine. With the ATR as a controller though you
have to punch another index hole in the disk or use a standard mech with
dual sets of index hole sensor such as those 'flippy' drives made by
Pertec and Aerocomp -never seen em', I just know they made them.

And then there are these freaky 3" disks I have for an Amstrad I once



In <10110302019.ZM26540_at_mindy.dunnington.u-net.com>, on 10/30/01
   at 08:19 PM, pete_at_dunnington.u-net.com (Pete Turnbull) said:

>On Oct 30, 10:32, Fred Cisin (XenoSoft) wrote:

>> 3.5" 1.4M (I have NEVER seen a 1.44M format!) are also at 300RPM

>However, many original 3.5" (SSDD not HD) ran at 600rpm, but with 2x the
>normal data rate (so the disks could also be used in 300rpm drives at
>normal data rates).

Jeffrey S. Worley
Asheville, NC USA
Received on Tue Oct 30 2001 - 16:17:27 GMT

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