JPH0318262B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a digital cassette deck used as an external storage medium for a microcomputer, and is particularly intended to prevent the tape from running out during writing of new data.

In a small-scale microcomputer system that uses a cassette tape as an external storage medium, the tape runs out while data is being written from the microcomputer's main memory (RAM) to the cassette tape (remaining tape capacity becomes zero). We must avoid this as much as possible. This is because data is only transferred unilaterally from the microcomputer to the cassette tape, and there is no function to determine whether all data has been written to the tape. If a microcomputer system has a large RAM capacity, it is possible to immediately read the data recorded on the tape and check it against the data in the RAM, but this is only possible if a reel-to-reel tape deck with separate recording and playback heads is used. Due to space constraints, a cassette deck that also serves as a recording and playback head cannot read and check previously written data while writing data from a microcomputer. Therefore, if data is transferred from the microcomputer to the cassette deck when there is insufficient tape remaining, the data will not be stored on the tape at all from the middle. As a result, when the microcomputer subsequently reads out the data from the tape, some of the data has been lost and is incomplete, resulting in a system down.

The present invention attempts to prevent the above-mentioned tape breakage during writing. The digital cassette deck of the present invention detects the remaining amount of cassette tape from the rotational speed of the reel, and detects when the remaining amount of tape falls below a certain value when attempting to write new data to the cassette tape from the outside. If the cassette tape is being stored, the cassette tape is ejected and an error message is displayed to prohibit writing of the data, and if the remaining amount of tape falls below the certain value while data is being written from an external source, writing is allowed to continue. This will be described in detail below with reference to the illustrated embodiments.

FIG. 1 is a schematic configuration diagram of a digital cassette deck showing an embodiment of the present invention, in which 10 is a display used for a tape counter, 11 is a driver for amplifying a seven segment signal, and 12 is a timing for dynamic display. Driver for amplifying the signal, 1
3 is a reel motor, 14 is its driver, 15 is a capstan motor, 16 is its driver, 17
18 is a solenoid for switching the tape running direction, 18 is a solenoid for switching the running speed, 19 _R and 19 _L are the right reel and left reel, and 20 _R and 20 _L are the N and S poles arranged alternately on their bottoms. Hall iC detects the rotation of reels 19 _R and 19 _L from changes in magnetic flux,
21 is a deck controller using a microcomputer; 22 is a tape counter that indicates how many times the reel has rotated; 23 is a tape remaining amount counter that indicates the remaining amount of tape; 24 is a cassette error indicator that indicates an insufficient amount of tape remaining; 31- 35 is various function keys. Among the function keys 31 to 35, 31 is a play (PLAY), 32 is a fast forward (FF), 33 is a rewind (REW), 34 is a stop (STOP), and 35 is a counter reset (COUNTER RESET) instruction key.
By pressing any of these keys, the SW signal is input to the deck controller 21. The deck controller 21 performs various processes shown in the general flowchart of FIG. 2 in response to key inputs.

FIG. 3 is an explanatory diagram of the tape counter 22.
This counter 22 is a RAM in the controller 21.
4 using part of (random access memory)
Consisting of counters 1 to 4 in stages, counter 1 in the first stage
is incremented (+1) each time the Hall pulses HPR or HPL (for example, 4 pulses per reel rotation) are input from the Hall _iC20R or _20L in FIG. For counters 2 to 4, counter 4 is the most significant digit, and depending on the carry output of the lower digit, +1 (when counting up) or -
1 (when counting down), representing a 3-digit tape counter in total. FIG. 4 shows the operation flow.

The tape counter 22 simply detects how many times the reel 19 _R or 19 _L has rotated by counting the number of hole pulses HPR or HPL, but the remaining amount counter 23 calculates the remaining amount of tape from the period of the pulse. used to ask for. However, since both use the same pulse, the controller 21
After completing the interrupt processing of the tape counter shown in FIG. 4, the processing of the remaining amount counter shown in FIG. 5 continues. The remaining amount of tape (TAPE) can only be detected while the reel is rotating. And FF or
REW high-speed running status and PLAY or REC (recording)
In low-speed running conditions, the reel rotation speeds are different even if the remaining amount of tape is the same, so it is necessary to process them separately.
In addition, regardless of whether the reel on the take-up side or the supply side is targeted, in the auto-reverse type, reel 19
Since _R and 19 _L can be on the winding side or the supply side depending on the running direction of the tape, it is determined which one to use (for example, the supply side reel is always used).

If two Hall pulses HPR or HPL occur in succession, for example, the interval (period) of their rise times can be measured, and from this the calculation (or conversion) described later can be performed to determine the remaining amount of tape. . In FIG. 5A, the tape remaining amount counter 23 is configured by software by setting an edge flag that is set at the rising edge of the Hall pulse and reset at the falling edge. That is, when the hole pulse is selected, it is determined whether the edge flag is 1 (set state) or not, and if it is 0, it is set, the previous value of the remaining amount counter is stored elsewhere, and the remaining amount counter is reset. After this, when the same routine is passed, the edge flag is 1, so the remaining amount counter measures one cycle of the Hall pulse (remaining amount counter + 1). This becomes the new stored value. This stored value is updated every time a Hall pulse occurs, and it is determined whether new digital data can be written in the flow shown in FIG. 5B. This flow applies only when an audio cassette deck is used as a digital cassette.
Prior to writing digital data, it is determined whether a signal (rec in progress) has come from the CPU (central processing unit). If so, it is determined whether recording is possible or not, and it is also determined whether the stored remaining amount counter value (stored value) is greater than or equal to a certain amount (constant). This constant is determined by the RAM capacity and transfer rate (baud rate) on the CPU side, but it may be determined that the remaining capacity is approximately 10 seconds. If the stored value is smaller than the constant, a Rec enable flag is set to notify the CPU that writing is possible, but if the stored value is larger than the constant, a cassette ejection flag is set and a cassette error is displayed. The latter not only lights up the display 24 in FIG. 1, but also informs the CPU. However, even if the remaining amount of tape falls below a certain value during writing, this error is not displayed and writing continues. This is because even if this is done, the current writing will not cause the tape to run out. Note that since the stored value actually increases as the remaining tape amount decreases, the true remaining tape amount is the value obtained by subtracting the stored value from a constant value.

The tape remaining amount counter can also be configured by hardware as shown in FIG. For details, please refer to the special application published in 1983.
118615, so we will provide an overview here. As mentioned above, the Hall iC20 _R and 20 _L convert changes in the N and S poles according to the rotation of the reels 19 _R and 19 _L into Hall pulse trains HPR and HPL, but one of these pulse trains is switched. Selected by circuit 41. The selection conditions of the switching circuit 41 depend on the running directions A and B of the tape. The reference oscillator switching circuit 42 selects the long-period pulse train SPB of the reference oscillator 39 during PLAY, and selects the short-period pulse train SPN of the reference oscillator 40 during FF and REW. The counter 44 counts the number of reference pulses SP supplied from the switching circuit 42 to the clock terminal CK during one cycle of the Hall pulse HP output from the switching circuit 41, for example, from being cleared at the rising edge until being cleared again at the next rising edge. Count. Hall Pulse HP 1
If the period is on the order of several 100ms, the reference pulse SP
is set to ms order, for example. counter 44
Since the counted value of is transferred to the latch circuit 45 for each cycle of the Hall pulse HP, in order to ensure this, the timing of the Hall pulse HP supplied to the clear terminal CLR of the counter 44 is controlled by the delay circuit 43. The timing is slightly delayed from the timing at which the circuit 45 is activated. The value in the latch circuit 45 is a pulse
Since it is binary data indicating one cycle of HPR or HPL, it corresponds to the stored value described above. HD is a recording/playback head, PR is a pinch roller, CAP is a capstan, and TP is a cassette tape.

FIG. 7 is a characteristic diagram showing the relationship between playing time and the period of the Hall pulse, and is shown for a C-30 tape with a thick hub and a C-60 tape with a thin hub. Since the Hall pulse period in this characteristic diagram increases with the passage of playing time, this is a characteristic diagram for the take-up reel. If the Hall pulse from the supply reel is employed, its period will decrease with the passage of playing time. In any case, if such a characteristic curve is known in advance, it is possible to calculate the remaining performance time, and therefore the remaining amount of tape during recording, from the Hall pulse period at each point in time.

As described above, according to the present invention, the remaining amount of tape is determined from the rotational speed of the reel, and when the value falls below a certain value, writing of new digital data is prohibited, so that the present cassette deck can be used as an external storage medium. This prevents the inconvenience of the tape running out while the CPU used as the tape is writing data. Furthermore, even if the remaining amount of tape falls below a certain value during data writing, writing continues, so the cassette tape can be used as effectively as possible.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram showing an embodiment of the present invention;
Figure 2 is a general flowchart showing the overall operation, Figure 3 is an explanatory diagram of the tape counter, Figure 4 is its flowchart, Figure 5A is a flowchart of the tape remaining amount counter, and Figure 5B is a new one. Figure 6 is a configuration diagram of the tape remaining amount counter using hardware.
The figure is a characteristic diagram showing the relationship between the playing time (remaining amount of tape) of the cassette tape and the rotational speed of the reel. In the figure, 19 _R and 19 _L are reels, 20 _R and 20 _L are hall iC, 21 is a deck controller, 23 is a tape remaining amount counter, 24 is a cassette error indicator, and TP is a cassette tape.

Claims (1)

[Claims] 1 The remaining amount of cassette tape is detected from the rotational speed of the reel, and if the remaining amount of tape is less than a certain value when attempting to write new data to the cassette tape from the outside, the cassette tape is When the tape is ejected, an error is displayed and writing of the data is prohibited, and if the remaining amount of tape falls below the certain value while data is being written from an external source, writing is allowed to continue. A digital cassette deck.