What's the deal with cassette tape counters?

What are tape counters actually counting? And why do they never seem to match up from one recorder to another? Did anyone ever try to standardize them? Let's find out... Time flow: 0:00 Introduction 2:12 Portable recorders 7:12 Vintage decks 10:36 High-end decks 13:15 Double decks 16:06 New decks 17:07 A de facto standard? 18:47 The 2X counter 24:22 Conclusion Correction: The TEAC W-1200's counter measures the supply spindle, not the takeup spindle. So it doesn't conform to what I call the "de facto standard" for tape counters after all, but it would match ICIA 2X counter readings if you divided its counter readings by four. #tape #counter #cassette