Have you used your calculator for something that was not really math related?

[Dieter]

(03-02-2019 05:31 PM)ijabbott Wrote:  AFAIK, the compact cassette has a constant tape speed of 1+7/8 in/s (4.7625 cm/s) so the tape counter ought to be geared from that. But the linear relationship time as be change in counter value would like reasonably vary between models.

The point here is that the value of the tape counter is proportional to the number of revolutions of of the reel, i.e. it first counts faster and continuosly slows down. This is because there is less and less tape on that reel while the speed has to be kept constant. The reel diameter decreases while the circumference per second must always be the same: 1 7/8 in/s. That's why the mathematical relation for a counter => time program has to consider the tape thickness, which in turn means that C60, C90 and C120 cassettes require different parameters.

Finally the 1980s brought tape decks with real time counters, which (mostly) not only worked in playback mode but also during fast forward and rewind. A friend of mine owned an Onkyo TA-2055 (a 1982 model) where I always admired the real time counter.

BTW, I also wrote such a program for my 41C. Instead of investigating the mathematical relations I did a simple nonlinear regression. ;-)

Dieter