Subject: Re: Creating new CP/M disks - Progress on IMSAI
From: M H Stein <dm561 at torfree.net>
Date: Sat, 12 Jan 2008 12:53:13 -0500
To: "'cctech at classiccmp.org'" <cctech at classiccmp.org>
Date: Sat, 12 Jan 2008 09:23:02 -0500
From: "Richard A. Cini" <rcini at optonline.net>
Subject: Re: Creating new CP/M disks - Progress on IMSAI
> As a matter of fact, the motor did run
constantly on many 8" drives (remember
> that many had 110V AC motors).
>
> m
Yes, but the heads engaged and disengaged to
reduce wear. On modern drives,
the heads remain engaged but the motor stops.
---------
Exactly; that's why you're having problems. But A & A seem to think
there's
something wrong with /MOTOR ON being on constantly, which can be quite
normal on an 8" FDC. Some FDCs do have an option to latch it ON with pin 16
and turn it OFF with pin 4 BTW.
Yes and when two sided drives were introduced the problem then was when the
head were lowered they could "clap" the media can sometimes bite it. Two
sided was a new set of problems.
In the 5.25"world motors were a problem as they were DC brush motors that
would wear both the brushes and the bearings (belt drive). Later drives
like the FD55s have a direct drive DC brushless motor that has none of
those problems.
Anyone ever guess at how long the media lasts with the motor turning and
head loaded in a clean environment? Months.
Allison