JPS63279467A - Write inhibit circuit for floppy disk drive - Google Patents

Abstract

PURPOSE:To attain back word compatibility being used for protecting a recording data on a conventional recording medium by enabling write only in a high density recording medium in which a servo information is written, prohibiting write in the conventional recording medium, and reproducing. CONSTITUTION:A detection means 5 to detect the presence/absence of a servo information in a recording medium, and a write inhibiting means 8 that inhibits a recording to a recording medium form which no servo information is detected are provided on the high density recording medium. In a high density recording medium, a servo information is written preliminarily at the time of formatting. Since no servo information is not written in the conventional recording medium, when no servo information is detected in said detection, the recording medium is judged to be a conventional one, and the write is inhibited by detecting the presence of the servo information. Therefore, such a back word compatibility that guarantees the protection of data for the conventional recording medium can be attained.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is a floppy disk drive that performs high-density recording and reproduction using servo information written in advance on the recording medium, which is an improvement over conventional recording media. The present invention relates to a write protection circuit for a floppy disk drive that allows only playback and guarantees data protection.

[Summary of the Invention] The present invention provides a floppy disk drive that performs high-density recording and reproduction using servo information written in advance on a recording medium, comprising: a detection means for detecting the presence or absence of servo information on a recording medium; By providing a write inhibit circuit for a floppy disk drive that is equipped with a write inhibit means that prohibits recording on recording media for which servo information is not detected, only playback is possible for conventional recording media that do not use servo information. It has achieved backward compatibility that enables data protection and guarantees data protection.

[Prior Art] In a conventional floppy disk drive (hereinafter referred to as FDD), a stepper positions a magnetic head to a recording track of a recording medium.

The recording track density (TPI) obtained by this method depends on the precision of the stepper, and there is a limit to its high density.

Therefore, in recent years, when formatting recording media,
An FDD has been proposed in which servo information is written in advance and tracking is performed using this servo information during recording and reproduction, thereby enabling high-density recording and reproduction.

In general, a buyer version FDD that performs high-density recording and playback is required to have backward compatibility that enables playback of conventionally used low-density recording media.

In contrast, high-density recording and
FDDs that perform playback can play back conventional recording media, but no special consideration has been taken to prevent writing to them.

[Problems to be Solved by the Invention] However, in the conventional FDI described above, the composition of the magnetic material and the characteristics of the magnetic head are different from those of the conventional recording medium, and so on. Correct writing to the recording medium is not guaranteed.

On the other hand, on the host system side that uses FDD,
A write command is sent regardless of what kind of recording medium is installed in the FDD.On the other hand, if the FDD has the same shape, it is not possible to identify whether it is a conventional recording medium based on the shape, so it cannot be used as a conventional recording medium. There is a risk that the data recorded on the device may not be protected.

The present invention was devised to solve the above-mentioned problems, and in FDDs for high-density recording and reproduction using servo information, it is possible to perform only reproduction without recording on conventional recording media. The object of the present invention is to provide a write protection circuit for a floppy disk drive that makes it possible to realize backward compatibility with guaranteed data protection.

[Means for Solving the Problems] In order to achieve the above object, the structure of the write-inhibiting circuit of the floppy disk drive of the present invention records and reproduces a high-density recording medium on which servo information is written, and the servo A floppy disk drive capable of playing back a recording medium on which no information is written includes a detection means for detecting the presence or absence of servo information on the recording medium, and a writing device for prohibiting recording on the recording medium in which the servo information is not detected. The invention is characterized by being equipped with prohibition means.

[Operation] The present invention focuses on the fact that servo information is written in advance on high-density recording media at the time of formatting, and that servo information is not written on conventional recording media, and detects the presence or absence of this servo information. Therefore, if servo information is not detected, it is determined that the medium is a conventional recording medium, and writing is prohibited.

[Example] Hereinafter, an example of the present invention will be described in detail based on the drawings.

FIG. 1 is a block diagram showing one embodiment of the present invention. The magnetic head 1 performs recording (writing) and reproduction on a recording medium mounted on the FDD, and is switched by a switch circuit 2 to perform either operation. This switch circuit 2 is switched by the write gate signal WRTGATE, and the write gate signal W RT G A
'r When E is present, it is set as the write operation side, otherwise it is set as the playback operation side.

A reproducing circuit 3 is provided on the reproducing side to amplify and filter the recorded signal of the recording medium taken out by the magnetic head 1. The recording signal sent from the reproducing circuit 3 is binarized by a comparator and a time domain filter circuit 4, and then subjected to time-based noise removal processing, and then sent as read data RDDATE via a system interface to, for example, the host system side. sent to.

The recording signal sent from the reproduction circuit 3 is inputted to the servo pattern detection circuit 5 on the other hand. Servo pattern detection is performed by detecting specific frequency signals, etc., as described later.
When it is detected, the detection output is made active. If a conventional recording medium on which no servo information is written is loaded and played back, this detection output will not become active. The presence or absence of this detection output is manually determined by the latch circuit 6.
Latched in value state. The output of this latch circuit 6 becomes a low (L) level when the detection output is active, and goes high (1-I) when the recording medium is taken out from the F'DD.
) level. Therefore, unless the detection output becomes active, it remains at H level.

The output of the latch circuit 6 is input to one input terminal to a NOR gate 7. The detection output of a write protection detection circuit 8 is connected to the other input terminal of this NOR gate 7, and when the protector of the attached recording medium is set, the switch 8a is turned off and the pull-up resistor RI raises the H level. is done manually. When at least one of six of these input nodes becomes I-level, the output of the NOR gate 7 becomes L level, and if any of the inputs are L level, it becomes H level. The output of this NOR gate 7 is sent as a write protect signal WRPRT that informs the system interface of write prohibition, and is also input to one input terminal of a NAND gate 8.

Next, the recording side will be explained. The recording side circuit is provided with a write circuit 9 and the aforementioned Nant gate 8. The write circuit 9 receives write data W from the system interface.
It receives RDATA, converts it to a predetermined recording level, and outputs a recording signal via the switch circuit 2 to the magnetic head 1 which has been switched to the recording operation side. The write gate signal WRTGT of the system interface is connected as a positive logic to the other input terminal of the Nant gate 8, which is an example of write inhibiting means, by an inverter 10, and if the output of the NOR gate 7 is at the I] level, the switch circuit is activated. The write gate signal WRTGAT, which is the output of the Nant gate 8 input to
Let E be L level. This write gate signal WRTGA
When TE is at the L level, the switch circuit 2
switch to recording mode. When the output of the NOR gate 7 becomes L level, the Nandt gate 8 is closed, and the output WRTGATE of the Nandt gate 8 is set to the FT level and the switch circuit 2 is switched to the reproduction operation side regardless of the presence or absence of the write gate signal WRTGT of the system interface. In this way, the write operation is inhibited by the output of NOR gate 7.

The operation of the embodiment having the above configuration will be described below. FIG. 2 is an explanatory diagram showing an example of servo pattern detection. Servo information 11 is recorded on recording track 12 in burst form.

The servo information recording portions 11a and Ilb are divided into two parts, and signals of different specific frequencies are recorded in each recording portion 11a and Ilb. If the magnetic head traces the track 12 accurately, the two specific frequency signals mentioned above will be detected equally when detecting servo information, but if the magnetic head traces the track 12 unevenly, it will be difficult to identify the side that is unevenly tracked. The frequency signal becomes larger and the other becomes smaller. Taking advantage of this fact, tracking is performed by coarsely moving the magnetic head with a stepper as in the past, and then finely moving the magnetic head by detecting servo information so that two specific frequencies are equally detected.

Therefore, by detecting one of these specific frequencies using a filter or the like, the servo pattern of this embodiment can be detected. According to the above-mentioned tracking, the track density (TP[) can be easily increased, for example, to about three times that of the conventional method.

The servo pattern detected in this way is binarized to indicate whether or not it has been detected, and is latched into the latch circuit 6 in FIG. Will it be done?
Or, if it is not latched because the servo pattern detection output is not activated in the latch circuit 6, the host system receives the write protect signal WRTPRT via the system interface. ) and reports write protection, closes the Nant gate 8, disables the write gate signal Wr (TGT) of the Sostem interface, and prohibits writing to the recording medium. Normally, the host system side detects the write protect signal. The write gate signal WRTGT is then dropped, but erroneous writing is prevented by prohibiting the write operation.

Write gate signal WRTGATE7! When l<H level, i.e., when no writing is instructed, the magnetic head l is playable and open, and due to the multiplex action, when a recording medium with a conventional recording density is loaded, writing is prohibited and only playback is possible. This enables backward compatibility with guaranteed data protection.

Note that various tracking methods using servo information have been proposed, and the present invention can be applied to any of these methods by making the servo pattern detection circuit suitable for the method. As described above, the present invention can be applied and implemented in various ways in accordance with its gist.

[Effects of the Invention] As is clear from the above description, the write inhibit circuit for a floppy disk drive of the present invention provides the following effects. In other words, in a floppy disk drive with a high recording track density, writing is enabled only on the high-density recording medium on which servo information is written, and writing is prohibited on conventional recording media, allowing only playback. It is possible to realize backward compatibility that protects recorded data on conventional recording media.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG. 2 is an explanatory diagram of servo pattern detection. 5... Servo pattern detection circuit (detection means), 8...
・Nant Gate (writing protection method).

Claims (1)

[Claims] A floppy disk drive capable of recording and reproducing a high-density recording medium on which servo information is written, as well as reproducing a recording medium on which servo information is not written. A write inhibiting circuit for a floppy disk drive, comprising: a detecting means for detecting the servo information; and a write inhibiting means for inhibiting recording on a recording medium in which the servo information is not detected.