This program is Copyright © 1997 by John H. Meyer and is used here by permission.

This program is supplied without representation or warranty of any kind. The author and The Museum of HP Calculators therefore assume no responsibility and shall have no liability, consequential or otherwise, of any kind arising from the use of this program material or any part thereof.

Tape Deck Counter to Time Converter |
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Shift | Input first counter calibration |
Input first time calibration |
Input second |
Input second time calibration |
Run calibration routine |

Label | Counter to Time |
Time to Counter |
Input counter, Enter: |
Add times in X, Y registers |
Subtract times in X, Y registers |

Key | A |
B |
C |
D |
E |

This program converts from the non-linear reading of a mechanical video or audio tape deck counter to elapsed time, and vice versa. For instance, if the tape counter reads 250, the program will compute that 19 minutes and 18 seconds have elapsed. Or, if the counter reading is 325 and a 4 minute 25 second track is to be recorded, the program computes that the counter reading will be 396 at the end of the passage.

The basic equation used is:

t = K_{1}- K_{2}^{2}

where:

t = elapsed time

= tape counter
reading (assumed to have been reset to zero at beginning of tape)

K1, K2 = constants which depend on tape deck and tape cassette (or video
tape deck). These constants are determined automatically by the calibration
routine in the program

For best results when running calibration program, read counter at two different times: Approximately half-way through the tape, and near the end of the tape. Program displays "error" if counter or time reading are greater than allowed by tape deck-tape combination (e.g., input 53 minutes for a 46 minute tape will give an error). All times are expressed in "minutes.seconds". Calibration factors can be stored on seconds side of card.

You have a TDK SA-90 cassette (46 minutes per side, nominal). At 23 minutes into the tape (approximately half way), the counter reads 305. At 44 minutes (near the end), the counter reads 704. Compute K1 and K2.

- Type "305" and press [f] [A].
- Type "23" and press [f] [B].
- Type "704" and press [f] [C].
- Type "44" and press [f] [D].
- Press [f] [E] to compute the constants.
- Optional: [RCL] [8] to recall K1.
- Optional: [RCL] [9] to recall K2.

Tape reads 423. How much time has elapsed?

Type "423". Press [A]. The display shows "30.17" (i.e., 30 min., 17 sec. has elapsed.)

Tape reads 490. You have a record with an eleven minute twenty-seven second cut. How much time is left on the tape (i.e., will the passage fit?). What will the counter reading be after the new recording is added?

Type "46". Press "Enter". Type "490". Press [A]. Press [E] (to subtract the two times). Answer (with calibration factors shown above): 11 minutes, 59 seconds.

To get counter reading, type "490". Press "Enter". Type "11.27". Press [C]. The answer is 742 (again assuming the calibration factors computed above).

You can save the calibration factors for future, typically on the second side of the card you use for the program (which uses only one side). To do this, make sure your calibration factors are in registers 8 and 9. Then, enter the following:

[f] [CHS]

[f] [EEX]

[f] [CHS]

[f] [ENTER]

The display will indicate: Crd. Insert your card into the reader.

The next time you use the program, load both sides of the card, and you won't need to re-calibrate.

LINE CODE KEYS KEYSTROKES (67) COMMENTS 001 31 25 11 Label A [f] [LBL] [A] 002 33 07 STO7 [STO] [7] 003 34 08 RCL8 [RCL] [8] 004 71 x [x] Compute t 005 34 07 RCL7 [RCL] [7] 006 32 54 X^{2}[g] [X^{2}] 007 34 09 RCL9 [RCL] [9] 008 71 x [x] 009 51 - - 010 32 74 Change to H.MS [g] [->H.MS] 011 23 02 Display 2 [DSP] [2] 012 35 22 RTN [h] [RTN] 013 31 25 12 Label B [f] [LBL] [B] 014 31 74 H.MS-> [f] [H <-] 015 34 09 RCL9 [RCL] [9] 016 71 x [x] Compute q 017 04 4 4 018 71 x [x] 019 34 08 RCL8 [RCL] [8] 020 32 54 X^{2}[g] [X^{2}] 021 35 52 X<>Y [h] [X<>Y] 022 51 - - 023 31 54 sqrt [f] [sqrt] 024 34 08 RCL8 [RCL] [8] 025 35 52 X<>Y [h] [X<>Y] 026 51 - - 027 02 2 2 028 81 ÷ ÷ 029 34 09 RCL9 [RCL] [9] 030 81 ÷ ÷ 031 23 00 Display 0 [DSP] [0] 032 35 22 RTN [h] [RTN] 033 31 25 13 Label C [f] [LBL] [C] 034 35 52 X<>Y [h] [X<>Y] 035 31 22 11 GSBA [f] [GSB] [A] 036 35 83 H.MS+ [h] [H.MS+] 037 31 22 12 GSBB [f] [GSB] [B] Compute q' 038 23 00 Display 0 [DSP] [0] 039 35 22 RTN [h] [RTN] 040 31 25 15 Label E [f] [LBL] [E] Compute t1-t2 041 42 CHS [CHS] 042 31 25 14 Label D [f] [LBL] [D] Compute t1+t2 043 35 83 H.MS+ [h] [H.MS+] 044 23 02 Display 2 [DSP] [2] 045 35 22 RTN [h] [RTN] 046 32 25 15 Label e [g] [LBL f] [e] Solve two 047 34 12 RCLB [RCL] [B] simultaneous 048 31 74 H.MS-> [f] [H<-] equations 049 33 06 STO6 [STO] [6] for 050 34 14 RCLD [RCL] [D] K1 and K2 051 31 74 H.MS-> [f] [H<-] 052 33 07 STO7 [STO] [7] 053 34 11 RCLA [RCL] [A] 054 32 54 X^{2}[g] [X^{2}] 055 34 13 RCLC [RCL] [C] 056 71 x [x] 057 34 13 RCLC [RCL] [C] 058 32 54 X^{2}[g] [X^{2}] 059 34 11 RCLA [RCL] [A] 060 71 x [x] 061 51 - - 062 34 11 RCLA [RCL] [A] 063 32 54 X^{2}[g] [X^{2}] 064 34 07 RCL7 [RCL] [7] 065 71 x [x] 066 34 13 RCLC [RCL] [C] 067 32 54 X^{2}[g] [X^{2}] 068 34 06 RCL6 [RCL] [6] 069 71 x [x] 070 51 - - 071 35 52 X<>Y [h] [X<>Y] 072 81 ÷ ÷ 073 33 08 STO8 [STO] [8] 074 35 53 Roll Down [h] [roll dn] 075 34 11 RCLA [RCL] [A] 076 34 07 RCL7 [RCL] [7] 077 71 x [x] 078 34 06 RCL6 [RCL] [6] 079 34 13 RCLC [RCL] [C] 080 71 x [x] 081 51 - - 082 35 52 X<>Y [h] [X<>Y] 083 81 ÷ ÷ 084 33 09 STO9 [STO] [9] 085 35 22 RTN [h] [RTN] 086 32 25 11 Label a [g] [LBL f] [a] Store 1 087 33 11 STOA [STO] [A] 088 35 22 RTN [h] [RTN] 089 32 25 12 Label b [g] [LBL f] [b] Store t1 090 33 12 STOB [STO] [B] 091 35 22 RTN [h] [RTN] 092 32 25 13 Label c [g] [LBL f] [c] Store 2 093 33 13 STOC [STO] [C] 094 35 22 RTN [h] [RTN] 095 32 25 14 Label d [g] [LBL f] [d] Store t2 096 33 14 STOD [STO] [D] 097 35 22 RTN [h] [RTN]

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