8 Sep
2013
8 Sep
'13
11:48 a.m.
It is possible to create non-integer ratios. They do have
to be rational ratios though. Still, it wouldn't take much code
to detect the index pulse and use that as a starting location
If one knew the actual sector pulse timing, one could use that
to correct a software DLL while it was rotating and not even have
to wait for a complete revolution.
As chuck says, this could be done with a simple PLL as well.
Not rocket science in either case.
For the H89 Heathkit, there is a simple uP board available
( or at least it was available ) to create sector pulses so one
could use a soft sector disk and drive with the H89 hard sectored
controller.
It's been done.
Dwight
Date: Sun, 8 Sep 2013 11:23:57 -0700
From: aek at bitsavers.org
To: cctalk at classiccmp.org
Subject: Re: Soft Sectoring a RK05
On 9/8/13 10:47 AM, Chuck Guzis wrote:
I'm with Tony on this one, however.
There's a "mystery" aspect to using an MCU for this sort of thing (i.e.,
code, programming). Index can be isolated from sector pulses with a simple one-shot (as
is
done on old 8" drives with separate sector and index lines). The rest is a simple
PLL setup with a divider. Robust, contemporaneous with no mystery at all. It could just
as well have been designed
and implemented in 1972 as today.
example patent
3898690_Pertec
under pertec/patents