Memorex 102 20MB Hard disk

Tom Gardner thomas.gardner at
Mon Apr 12 13:04:42 CDT 2010

> ------------------------------
> Message: 18
> Date: Sun, 11 Apr 2010 14:25:09 -0400 (EDT)
> From: Steven Hirsch <snhirsch at>
> Subject: Memorex 102 20MB Hard disk
> To: Classic Computers Mailing List <cctech at>
> Message-ID: <alpine.DEB.2.00.1004111405140.3802 at duo>
> Content-Type: TEXT/PLAIN; format=flowed; charset=US-ASCII
> Has anyone on the list seen or work with one of these?  I received a
> Morrow M-20 8-inch hard disk along with my N* Horizon and found the
> Memorex 102 disk mechanism inside (what a beast!).

I worked on the 101/102

01_jan83.pdf for the Memorex 112 Technical Manual; the 112 is a later
version of the 102 and they probably have a lot in common.  Paragraph 1.2.2
shows the typically current wave forms which should be the same.

According to the spec the start up current is 6A peak and 1.6A running.  So
when running yr 10 ohm is only 1/4 watt and should be cool.  The peak power
of less than 3.6 watts should only last a very short time as the motor comes
up to speed and it's back EMF lowers the current to the running current of
well under 1.6A (the running current supplies both the spindle motor and the
stepper motor).  Again the figure shows a spindle motor start up current of
about 4.5A and the peak 6A occurs during stepping.

Good luck.

BTW, if you have an 102 documents I would really like a copy, personally or
at bitsavers.


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