recovering cartridge tapes (was: Tek fiches found! (was: Looking for
philip at axeside.co.uk
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.
More information about the cctech