----------------------------------------
  From: spectre at 
floodgap.com
 Subject: Re: tape "load and save" to a PC/Mac
 To: cctalk at 
classiccmp.org
 Date: Wed, 18 Nov 2009 07:17:21 -0800
  Hi
 It might be the phase of the signal that counts.
 The Poly88 used a manchester encoding and It had
 a switch to select the right phase ( normal or inverted ). 
 But wouldn't the sync mark handle getting the proper phase (i.e., the
 adjustment to properly read the pulses)? Or do I misunderstand what you're
 referring to by phase?
 
Hi
 No, it doesn't in the Poly88. Each recorder has a different
number of inversions. The manchester encoding is sensitive
to the phase. The pulses may be a fast rise and slow fall.
This would also make it phase sensitive as well.
 Think in terms of a logical inverter only for the audio.
Imagine a pulse detector that is looking for rising edges
and then invert the data. Since it is looking for the
time between pulses, it would be completely wrong.
Dwight
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