JPH06325436A - Method for storing data on magnetic tape - Google Patents

Abstract

PURPOSE:To make it possible to set and recognize a more exact logical tape end LEOT with a data recorder using a magnetic tape. CONSTITUTION:While a tape remaining amt. is monitored, data is written on the magnetic tape. The logical end of the tape, when detected, is reported to a host computer. A provisional logical end LEOT (A) is preset as the tape position slightly before the actual logical end. The tape is fast fed to a physical tape end when the tape position arrives at the position of the provisional logical end LEOT (A). The tape amt. from the provisional end LEOT (A) to the physical tape end is determined. The true logical end LEOT (C) is set in accordance with the determined tape amt. The data writing is, thereafter, returned to the provisional LEOT (A) and is executed up to the true LEOT (C). The reporting of the LEOT to the host computer is executed at the true LEOT (C).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data storage method on a magnetic tape suitable for use when a DAT (digital audio tape recorder) is used as a data recorder.

[0002]

2. Description of the Related Art A DAT is a helical scan type magnetic tape recording / reproducing apparatus for audio signals. Recently, the DAT has been used as a data recorder for recording / reproducing data from a computer. .

When the DAT is used as a data recorder as described above, the data from the host computer is
DA converted to data with DAT format
It is recorded and reproduced at T.

In the DAT format, two tilted tracks formed on a magnetic tape during one rotation of the rotary drum by the two recording magnetic heads mounted on the rotary drum and having different azimuth angles are one. It is regarded as a frame. And 16-bit PCM audio data
It is divided into two parts of 8 bits each, and is interleaved in units of the above frames and recorded on the tape. Sub data is also recorded on each tilt track.

That is, FIG. 5 shows the track pattern of this DAT, and each inclined track 2 formed on the tape 1 by two recording heads as one frame.
A and 2B are a main area AM for recording PCM audio data and a sub area AS for recording sub data.
Each area is divided. As the sub data, an ATF signal for auto tracking servo, a sub code including a track address as a content, and the like are recorded.

FIG. 6 shows a tape format when the DAT is used as a data recorder.

The tape 1 is composed of a magnetic tape main body 3 and leader tape portions 4 and 5 made of a transparent material and connected to both ends of the main body 3. Although not shown, the tape 1 is stored in a cassette including a supply reel and a take-up reel, and is sequentially transferred from the supply reel to the take-up reel. The beginning of the magnetic tape main body, which is the connection end of the magnetic tape main body 3 and the leader tape portion 4 on the transfer start end side, is B
The end of the magnetic tape body, which is called the OM and is the connecting end between the magnetic tape body portion 1 and the leader tape portion 5, is E
Called OM.

[0008] The tape position after a predetermined length from the BOM is the logical start of the tape (called BOT).
The area between BOM and BOT is called the device area 4a, and nothing is recorded or a signal for testing the device is recorded. Next to the device area 4a is a 35-frame reference area 4d in which a signal indicating the start of data is recorded. Next to the reference area 4d, the history of the number of read / write operations and errors is recorded 1
The system area 4e has 15 frames. Next, a 23-frame area 4f called a vendor group follows the system area 4e. After the vendor group 4f, a plurality of group areas 4g each having 23 frames in which backup data from the host computer is recorded are provided. At the end of the data,
Data EOD indicating that is recorded for 300 frames.

The tape position that is a predetermined length before the EOM is the logical end of the tape (called LEOT). When the LEOT position is detected during data recording, the DAT as a data recorder reports the fact to the host computer. In response to this, the host computer recognizes that the physical tape end is near, and notifies the user. Then, for example, the user maintains the data by exchanging the cassette tape.

Conventionally, at the time of recording, the tape position of this LEOT is detected by calculating the remaining tape amount each time a predetermined amount of data is written, and whether or not the LEOT tape position has been reached based on the calculated remaining tape amount. I'm trying to decide. As is well known, the method of calculating the remaining tape amount is to provide the supply reel with a frequency generator that generates a frequency signal corresponding to the rotation speed of the supply reel and measure the cycle of the frequency signal to measure the tape at that time. The time T for one rotation of the supply reel at the winding diameter is obtained, and the projected area of the tape wound around the supply reel is obtained from this information and the tape thickness information known in advance.

That is, where t: tape thickness [mm] l: remaining tape length [mm] dh: reel hub diameter [mm] d: supply reel current tape winding diameter [mm], supply reel Area t of the remaining tape winding diameter
l becomes tl = π (d / 2) ² −π (dh / 2) ² (1).

Then, the tape speed sent out from the supply reel of the tape when the remaining tape amount is v [mm / se]
c], the tape remaining time is z, and the time of one rotation of the supply reel is T [sec], l = z · v (2) v = ω · d / 2 = π · d / T (because , Ω = 2π / T) (3) When the above equations (1), (2), and (3) are combined,
The tape remaining time z can be obtained, and the tape speed v
Then, by dividing this value z, the remaining tape length can be obtained.

[0013]

However, the above method for calculating the remaining tape amount cannot be ignored because the influence of the variations in the actual tape thickness t, the variations in the reel hub diameter, and other errors cannot be ignored. You must have a sufficient margin to detect. For this reason, conventionally, the detection of the logical end LEOT is set to be performed earlier as the tape position, and the tape cannot be effectively used.

In the case of the conventional method, the logical end L
The calculation of the remaining tape amount for detecting EOT must be performed accurately. Therefore, it is necessary to accurately obtain the time for one rotation of the supply reel, and for that purpose, it is better to obtain the average of a plurality of rotations of the supply reel.

When the writing of data is once stopped and then the writing is started again, it is necessary to perform tape running control and mode control similar to so-called continuous recording.
When rewriting, rewind the tape a predetermined amount,
The servo is started up and tracking control is performed until the end of the previous recording position, but in order to accurately obtain the one rotation time of the supply reel, the tape is rewound in addition to the predetermined tape amount. In the past, it was necessary to control the tape. Since this process is performed every time the rewriting is started, there is a drawback that the recording time becomes longer accordingly.

In view of the above points, the present invention provides a method capable of accurately detecting the logical end LEOT, enabling the use of the tape without waste, and shortening the recording time. The purpose is to

[0017]

In order to solve the above-mentioned problems, the method for storing data on the tape according to the present invention relates to the magnetic recording medium while monitoring the remaining amount of the tape when the reference numerals of the embodiments described later are made to correspond. In a data storage method that writes data to the tape and reports the fact to the host computer when the logical end of the tape is detected, a temporary logical position is set in advance as the tape position before the actual logical end. When the tape end is set and the tape position reaches the temporary logical end position, the tape is fast-forwarded to the physical tape end, and the tape amount from the temporary logical end to the physical tape end. Then, set the true logical end based on the calculated tape amount, and then return to the temporary logical end position and write the data. Performed until the true logical end, in true logical end, characterized in that to perform the end report to the host computer.

[0018]

In the present invention having the above-mentioned structure, at the time of recording,
When the tape position of the provisionally logical end is roughly set, recording is interrupted and the tape is fast-forwarded to the physical end of the tape, and at the same time from the provisional logical end to the physical tape end. The amount of tape up to is required.
From this determined tape amount, the true logical end tape position is set.

Thereafter, the tape position of the temporary logical end is returned to, recording is performed up to the true logical end, and when the true logical end is detected, the fact is reported to the host computer.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A data storage method according to the present invention will be described below with reference to the drawings by exemplifying a case where the DAT is used as a data recorder.

FIG. 1 shows an example of a system configuration when DAT is used as a data recorder.
Is a DAT, 101 is a system bus, 102 is a host computer, and 103 and 104 are local buses.

The DAT 100 is a recording / reproducing mechanical deck unit 1.
1, recording amplifier 12, reproduction amplifier 13, signal processing circuit 1
4, a data buffer RAM 15, a data controller 16, an interface board 17, a system controller 18, a servo and motor drive circuit 19, and the like.

Further, in this example, in the mechanical deck section 11 of the DAT 100, the supply reel rotating mechanism is provided with a frequency generator 11FG. Then, the frequency signal SFG having a frequency proportional to the rotation speed of the supply reel from the frequency generator 11FG is supplied to the servo and motor drive circuit 19 via the waveform shaping circuit 21 and to the tape amount and LEOT detection circuit 20. Supplied. The tape amount and LEOT detection circuit 20 may be included in the system controller 18.

Recording / playback mechanical deck section 11 of DAT 100
Includes a rotary head drum 11D. The magnetic tape 11T is wound around this drum in an angular range of about 90 degrees and is transported by a capstan and a pinch roller (not shown). The drum 11D includes two recording heads having different azimuth angles and two reproducing heads.
During one rotation of 1D, the two recording heads record data as two inclined tracks, and the two reproducing heads reproduce the recorded data.

At the time of recording, the buses 104, 101, 103
The data transmitted from the host computer to the DAT 100 via the interface is stored in the RAM 15 via the interface board 17 and the data controller 16.
Then, under the control of the system controller 18, the data in the RAM 15 is sent from the data controller 16 to the signal processing circuit 14 and converted into the DAT format. The converted data is recorded by the recording amplifier 12
It is supplied to the recording / reproducing mechanical deck section 11 via the recording medium and recorded on the magnetic tape by the recording head.

The data recorded on the magnetic tape is reproduced by the two reproducing heads and supplied to the signal processing circuit 14 via the reproducing amplifier 13. In the signal processing circuit 14, the DAT format data is restored to the original digital data and stored in the RAM 15. Then, the reproduced digital data includes the data controller 16, the interface board 17, and the buses 103, 101, and 1.
It is transmitted to the host computer 102 via 04.

As shown in FIG. 6, the data from the host computer 12 is sequentially recorded in the group area 4g consisting of 23 frames. The data from the host computer 102 is recorded as the data in the main area of each track.

At the time of recording, every time data is written in the group area 4g, it is checked whether or not the next group area is written and the logical end LEOT of the magnetic tape is reached or the LEOT is exceeded. As a result of the check, when it is detected that the logical end LEOT is reached or has passed, the system controller 18 reports to that effect to the host computer 102 and calls attention to the writing of the next data as the tape end is approaching. .

In this case, in the present invention, the tape position of the logical end LEOT is set accurately as described below. That is, in the present invention, a temporary logical end (temporary LEOT (A)) is set in advance. This temporary LEOT (A) is set as a rough tape remaining amount with a sufficient margin for the end EOM of the magnetic tape body. Since this is a temporary position for determining the true logical end LEOT (C), it may be roughly set in this way. As this value, for example, the remaining tape amount can be set at a position of about 5 m in terms of length.

Then, as shown in FIG. 2, during recording,
Each time writing to the group area 4g, the remaining tape amount is calculated from the time of one rotation of the supply reel. Therefore, as shown in FIG. 1, the frequency signal SFG proportional to the rotation speed of the supply reel from the waveform shaping circuit 21 is supplied to the cycle detection circuit 22, the cycle of the signal SFG is detected, and the signal is supplied from the detected cycle. The time T for one rotation of the reel is detected. Signal S
The FG is a signal of, for example, 24 cycles per one rotation of the supply reel, and 24 cycles of the signal SFG are added to detect the cycle of one rotation. For the sake of accuracy, the average is calculated from the information of a plurality of rotations of the supply reel.
It is not necessary to judge whether or not it is (A), since it may be rough.

The information on the detected time T of one rotation of the supply reel is supplied to the tape remaining amount calculation circuit 23, and the tape remaining amount is obtained according to the above-mentioned calculation formula. The obtained remaining tape amount is supplied to the temporary LEOT determination circuit 25 through the switch circuit 24 and compared with the temporary LEOT (A) from the temporary LEOT generation unit (for example, register) 26. Then, the determination circuit 25 determines whether or not the tape position is the position of the temporary LEOT (A), and when it is detected that the tape position of the temporary LEOT (A) is detected, the detection signal is sent to the system controller 18. Supply.

The system controller 18 uses this temporary LE.
When the position detection signal of OT (A) is input, the recording operation is stopped and the tape is fast forwarded to the end of the physical tape. At this time, at the tape position of the temporary LEOT (A), the wave number measuring circuit 27 including a counter is set by the system controller 18 and fast-forwarded.
Frequency signal SFG from T (A) to end of physical tape
The wave number of is measured. The wave number of the measurement result is supplied to the system controller 18, and from this wave number, the system controller 18 obtains the tape amount from the temporary LEOT (A) to the physical tape end. The tape amount can be either time or tape length, but it is calculated as how many frames the tape amount in this period corresponds to. At this time, the leader tape part is excluded.

The system controller 18 uses this temporary LE.
Based on the tape amount from OT (A) to the end of the physical tape, the true LEOT (C) is set as, for example, the remaining tape amount, and the true LEOT (C) is, for example, a register. Write in. True LEOT
The tape position of (C) is such that the position between this position and the end of the physical tape satisfies the standard when DAT is used as a data recorder.

After that, the system controller 18 returns to the position of the temporary LEOT (A). The position of the temporary LEOT (A) can be detected from the subcode recorded on the track. When the temporary LEOT (A) is returned to, the recording is restarted. Upon restarting the recording, the system controller 18 switches the switch circuit 24 to a state opposite to the state shown in the drawing.

Then, the cycle detection circuit 22 obtains the time for one rotation of the supply reel again each time data is written in the group area, and the tape remaining amount calculation circuit 23 obtains the tape remaining amount. In this case, since the switch circuit 24 has been switched, the information on the obtained tape remaining amount is obtained from the true LEOT generation unit 28 in the true LEOT determination circuit 29.
Is compared with the true LEOT (C), and when the next group area is written, it is determined whether or not the tape position of the true LEOT (C) has passed. When it is detected that the position of the true LEOT has passed, the detection output to that effect from the determination circuit 29 is supplied to the system controller 18.

In response to this, the system controller 18 reports the LEOT detection to the host computer.

In this case, after the true LEOT (C) is obtained, the switch circuit 2 is used until the tape is replaced.
4 is switched to the discriminating circuit 29 side.
In addition, fast forward is performed from the position of temporary LEOT (A), and true L
It takes about 10 seconds to detect EOT (C) and then return to the temporary LEOT (A) and restart recording.
Moreover, since the operation of detecting the true LEOT (C) is performed only once with one tape, the execution speed of recording is not so affected as a whole.

FIG. 3 is a flow chart showing an example of an operation control routine including the operation of the circuit 20 until the system controller sets true LEOT (C).

This routine 200 is true LEOT (C).
Is set every time the writing of the group area is completed before the setting is made, and the process proceeds from step S1-1 to step S1-2. In step S1-2, the remaining tape amount is obtained from the cycle of the frequency signal SFG proportional to the rotation side of the supply reel, and in the next step S1-3, the tape position is before the temporary LEOT (A) (A). It is determined whether or not. If the result of the determination is that it is before the temporary LEOT (A), this routine is exited from step S1-4. If it is determined that the temporary LEOT (A) has passed, the process proceeds to step S1-5.

In step S1-5, the tape is rewound. Next, in step S1-6, when it is detected that the tape has reached the end, the process proceeds to step S1-7,
A tape amount between the tape position of the temporary LEOT (A) and the physical tape end is obtained. Next, in step S1-8, a true LEOT that conforms to the standard is obtained from the obtained tape amount.
Set the tape position in (C).

Next, in step S1-9, the tape is rewound. At this time, the subcode is obtained from the reproducing head, and rewinding is performed while searching the tape position. Then, in step S1-10, the tape position is the temporary LEO.
When it is detected that the position is T (A), the process proceeds to step S1-11 to stop the rewinding, and in the next step S1-12, write the subsequent data to the temporary L
Restart from EOT (A). Then this routine 20
Exit 0.

After the true LEOT (C) is set as described above, the routine 200 of FIG. 3 is no longer executed until the tape is replaced, and the routine 300 shown in FIG. 4 is used for recording. , Is called and executed each time writing of the group area 4g is completed.

That is, when this routine 300 is called in step S2-1, step S2-2
In step S2-3, when the next group area 4g is written, it is determined whether or not the tape position passes the true LEOT (C). The remaining tape amount can be calculated from the cycle of the frequency signal SFG proportional to the rotation side of the supply reel, but in this example, the temporary LEOT (A) and the true LEOT (C) are used.
Since the tape amount between and can be recognized as the number of frames, it is determined as the number of frames remaining until the true LEOT (C). If the result of the determination is that it is before the true LEOT (C), step S2
The routine 300 is exited from -4.

If it is determined that the true LEOT (C) has passed, steps S2-3 to S2-5.
Then, the write operation is interrupted. Then, in the next step S2-6, it is reported to the host computer that the true LEOT (C) of the tape has been detected, and in step S2
This routine 300 is exited from -7.

Although the present invention is applied to the case where DAT is used as a data recorder, the present invention is not limited to this case, and a data recorder that uses a magnetic tape to back computer data is used. Needless to say, it can be applied to the data storage of.

[0046]

As described above, according to the present invention, at the time of recording, the provisional LEOT which is roughly determined is set.
When the tape position of (A) is reached, the tape is fast-forwarded to the physical tape end, the tape amount from the temporary LEOT (A) to the physical tape end is measured, and the true LEOT tape position is based on the measured value. Since the setting is made, the tape can be used without waste.

The true LEOT position can be accurately reported to the host computer regardless of variations in tape thickness and the like.

Until the true LEOT is set,
Since it suffices to monitor whether or not the rough temporary LEOT (A) tape position has been reached, it is not necessary to detect the remaining tape amount as a very accurate value. Therefore, the supply reel can be accurately measured for the remaining tape amount. Therefore, there is no need to rotate it extra, and the recording time as a whole can be shortened accordingly.

[Brief description of drawings]

FIG. 1 is a block diagram of an example of a DAT data recorder to which the method according to the present invention is applied.

FIG. 2 is a diagram for explaining a method according to the present invention.

FIG. 3 is a flowchart for explaining an example of a main part of the method according to the present invention.

FIG. 4 is a flowchart for explaining an example of a main part of the method according to the present invention.

FIG. 5 is a diagram for explaining a DAT tape pattern.

FIG. 6 is a diagram for explaining a format of a DAT data recorder.

[Explanation of symbols]

 100 DAT 101 System Bus 102 Host Computer 20 Tape Remaining Amount and LEOT Detection Circuit 25 Temporary LEOT Discrimination Circuit 26 Temporary LEOT Generation Section 28 True LEOT Generation Section 29 True LEOT Determination Circuit

Claims (1)

[Claims] 1. A data storage method for writing data to this magnetic tape while monitoring the tape remaining amount, and reporting the fact to a host computer when the logical end of the tape is detected. A temporary logical end is set in advance as the tape position before the physical end, and when the tape position reaches the temporary logical end position, the tape is fast-forwarded to the physical tape end. , Calculate the tape amount from the temporary logical end to the physical tape end, set the true logical end based on the calculated tape amount, and then return to the temporary logical end position and write the data. To the true logical end, and at the true logical end, report the end to the host computer. Storage method.