Re: MFM drive gone nuts

From: Julian Perry <>
Date: Sun, 20 Jul 2014 09:45:23 +1000
Message-ID: <>
That's a Miniscribe 3650, I presume. (Or it's RLL brother, 3675)
I sold many of them back in the 80's, and I'm quite familiar with
them. It's been left in burn-in test mode.

I THINK the first three jumpers have to be in place for normal
operation - if one's nicked, it goes into one of several test modes.
One is a "fanout" seek test, the other a random, another a sequential
step test. it's been a VERY long time between drinks.

Have a play with the first 3 jumper positions (the ones on the edge
over the narrow edge connector).




> On 07/19/2014 07:38 PM, Michał Pleban wrote:
>> Remember again that this is without the controller attached. Attaching
>> the controller, the controller to the computer etc. has no effect. The
>> computer is unable to communicate with the drive as it performs its head
>> dance - all operations result in timeout.
>> Do you possibly have any idea what is going on with the drive? I thought
>> that maybe it doesn't like the voltage from the CBM710 PSU, but I doubt
>> it - the whole computer runs on it flawlessly (including the floppy
>> drive). Or maybe something was broken when I attached the CBM610 PSU and
>> learned that it is too weak to spin the drive? But in any case, this
>> would be very strange symptoms of a power failure.

> All the drives I have seen have some kind of microcontroller on them. 
> Along the lines of a 8049 or 8051. Take a closer look what you find on
> your drive. Could be an EPROM-based controller (e.g. 8751) that is 
> slowly losing the contents of the EPROM part due to age.

>   Gerrit

>        Message was sent through the cbm-hackers mailing list

Best regards,

       Message was sent through the cbm-hackers mailing list
Received on 2014-07-20 00:00:02

Archive generated by hypermail 2.2.0.