JPH0748280B2 - Floppy disk device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a floppy disk device, and more particularly to a write-protection circuit for a recording medium when the floppy disk controller fails.

[Conventional technology]

Conventionally, in this type of floppy disk device, if the write gate signal sent from the floppy disk control device to the floppy disk device is in the active state, the data is recorded on the recording medium.

[Problems to be Solved by the Invention]

In the conventional floppy disk device described above, if the write gate signal remains in the active state due to a failure of the floppy disk control device, the data written in the recording medium may be inadvertently updated. Yes, there is a drawback that necessary data is destroyed.

[Means for Solving the Problems]

The present invention writes a write data sent from a floppy disk control device to a recording medium, and reads a read data recorded on the recording medium.
In the disk device, an ID address mark detecting means for detecting an ID address mark from the read data,
Pulse generation means for sending a pulse of a predetermined time width when the ID address mark detection means detects the ID address mark, and pulse generator means for detecting a data address mark from the read data. Means, a counter that counts a predetermined constant value from the time when the data address mark detecting means detects the data address mark when the pulse generating means is in an active state, and the pulse generating means. For writing data to the recording medium only in the active state or while the counter is counting and the first write gate signal sent from the floppy disk controller is in the active state. And a gate signal generating means for transmitting a second write gate signal.

〔Example〕

 Next, the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of a floppy disk device of the present invention.

FIG. 2 is a timing chart showing the operation of FIG. The numbers shown in FIG. 2 correspond to the numbers shown in FIG. 1, respectively. In FIG. 1 and FIG.
The floppy disk device 1 of the present invention comprises a first data separator 3a, a second data separator 3b, an ID address mark detection circuit 4, a data address mark detection circuit 5, a monostable multivibrator 6, and a first monostable multi.・ Vibrator 6a, second monostable multi ・
The first data separator 3a comprises a vibrator 6b, a counter 7, an OR gate circuit 8 and an AND gate circuit 9. The first data separator 3a is mounted on the floppy disk device 1, and the information written on the recording medium is read by a magnetic head (not shown). And read data 101 generated by a reproducing circuit (not shown) are input through a signal line, and a data discrimination signal, a so-called window signal 106, and synchronization that is synchronized therewith through two signal lines. The modified read data signal 105 is sent to the floppy disk controller 2 and the ID address mark detection circuit 4, respectively.

Here, 100 shown in FIG. 2 is a recording format for one sector in which the read data 101 is written on the recording medium, SYNC is a synchronization field of the first data separator 3a, IDAM is an ID address mark, and ID. Is an identifier with sector address recorded, GAP2 is a gap, DAM
Indicates a data address mark, DATA indicates an information recording field, and GAP3 indicates a gap.

Next, the ID address mark detection circuit 4 outputs the window signal 10
When 6 and the synchronized read data signal 105 are input and an ID address mark is detected, a positive pulse ID address mark detection signal is sent out from the signal line 107. Then, the monostable multi-vibrator 6 is triggered by the pulse sent to the signal line 107, and sends a pulse having a constant width to the signal line 111. On the other hand, the second data separator 3b receives the write data 102 from the floppy disk controller 2 via a signal line and receives a data discrimination signal, a so-called window signal 109, and a synchronization for synchronizing with the data discrimination signal via two signal lines. And the write data signal 108. Further, the data / address mark detection circuit 5 outputs the window signal 109
Further, the synchronizing write data signal 108 is input, and when the data address mark is detected, the data address mark detection signal of the positive polarity pulse is transmitted from the signal line 110. Subsequently, the counter 7 inputs the clock signal serving as the timing reference from the floppy disk controller 2 via the signal line 103, and the signal sent from the monostable multivibrator 6 via the signal line 111 goes high. When the data / address mark detection signal is at the level and is input from the data / address mark detection circuit 5 through the signal line 110, a high level signal is transmitted to the signal line 112 until a predetermined time is counted. Further, the signals of the signal lines 111 and 112 are input to the OR circuit 8, and the output signal of the OR circuit 8 and the floppy disk controller 2 are input to the AND circuit 9.
The first write gate signal is input from the signal line 104 through the signal line 104. Therefore, as shown in FIG. 2, even if the signal line 104 remains at the high level as shown by the broken line, the signal from the AND circuit 9 is output by the output to the signal line 112 which is the output of the counter 7. A regulated second write gate signal is delivered via line 113. Then, it is sent to the write circuit (not shown) of the floppy disk device 1.

〔The invention's effect〕

As described above, according to the floppy disk device of the present invention, even if the write gate signal remains in the active state due to the failure of the floppy disk controller, the data is written in the recording medium only in the monostable state.・
The high level period of the multi-vibrator or the counter is limited to the high level period, and there is an effect that the destruction of data on the recording medium can be suppressed to the minimum.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the floppy disk device of the present invention, and FIG. 2 is a timing chart showing the operation of FIG. 1 ... Floppy disk device, 2 ... Floppy disk
Disk controller, 3a ... first data separator, 3b ...
… Second data separator, 4 …… ID address mark detection circuit, 5 …… Data address mark detection circuit, 6 ……
Monostable multi-vibrator, 7 ... counter, 8 ... OR circuit, 9 ... AND circuit.

Claims (1)

[Claims] 1. A floppy disk device for writing write data sent from a floppy disk control device to a recording medium and reading read data recorded on the recording medium, and detecting an ID address mark from the read data. ID address mark detecting means, pulse generating means that becomes active when the ID address mark detecting means detects an ID address mark and sends out a pulse of a predetermined time width, and data address mark from the read data A data / address mark detecting means for detecting, and the pulse generating means in an active state,
Moreover, the data / address mark detecting means is
A counter that counts a predetermined constant value from the time when the address mark is detected, the pulse generating means is in an active state, or the counter is counting, and is sent from the floppy disk controller. And a gate signal generating means for transmitting a second write gate signal for writing data to the recording medium only during a period when the first write gate signal is in an active state. .