Paul Koning paulkoning at comcast.net
Tue Mar 9 19:39:31 CST 2021

> On Mar 9, 2021, at 8:32 PM, Chris Zach via cctalk <cctalk at classiccmp.org> wrote:
>> Really?  The very similar RS64, as well as the RS11, both had a formatter device that field service could use to write the timing tracks if they were lost.  Or, for that matter, if the platter had to be replaced, since it arrived from the factory totally blank.
> Oh, sorry, meant the data was lost. I don't think it had the formatter on the unit though.

Right, the formatter was a piece of field service hardware.  I think typically it had to be shipped up from Maynard, there wasn't enough call for them to have them at each field office.

One oddity is that the timing track clock frequency on those writers is variable.  The device would write the correct number of timing pulses and then read the timing track to verify the length of the gap at the end.  Lights would indicate whether the gap was too small, correct, or too long, and you'd adjust the frequency knob accordingly until the "ok" light came on.   It's documented in the maintenance manual.  I read it long before I saw it done, and was amazed that yes, it actually work just as strangely as what the manual claims.

Judging by the block diagram in the manual, you could build your own in an afternoon or two.

>> Sure, a generalization of Dave Gesswein's MFM emulator.  I was just looking the other day how practical it would be for such a device to do an RK05 emulation.  The answer seems to be: quite practical.
> The MFM emulator is an amazing bit of kit.

It certainly is.  It works wonderfully well.


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