| 摘要 |
Apparatus for use in correlating actual tape play times, tape length, or predetermined tape program locations with tape-spool revolution values provided by a tape-revolution index counter in a tape machine. The calculator has a lower circular base plate and a smaller, upper circular plate which rotates concentrically with respect to the lower plate. The base plate carries a scale corresponding to tape-spool revolution values indicated by the machine, and one or more time scales relating tape spool revolution values to actual tape-play times, and/or to remaining play times or program locations. A ratio marker and time scale indicator are positioned on the upper member such that alignment of the ratio marker with a selected tape-revolution value on the base plate brings the time scale indicator into alignment with the corresponding playing-time value on the base plate.
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