Creating new CP/M disks - Progress on IMSAI

[Allison]

>
>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


>m
>