recovering cartridge tapes (was: Tek fiches found! (was: Looking for

Philip Belben philip at
Thu Jul 22 11:58:13 CDT 2010

> IRIC the Tekky 405x series didn't use any of the standard encodings, 
> though. They had a 2 coil head that read/wrote 2 tracks at the same time. 
> A pulse on one track was a '0' bit,a pusle on the other track was a '1'. 
> Whether simultaneous pulses on both tracks were used as some kind of 
> marker I don;t know, many otehr similar systems did use that.

It was indeed.  Pulse on one track = 1, pulse on other track = 0, pulse 
on both tracks = marker.  The pulses on each track were alternately 
positive- and negative-going to minimise the dc component.

I have the spec somewhere.  Probably in one of my Tek service manuals.


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