JPS6129045B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in magnetic disk drives, and in particular to improvements in read-only switches (read-only switches).
This is related to preventing the operation of "onlyswitch" from interfering with online operations.

FIG. 1 is a block wiring diagram showing an example of a conventional magnetic disk device. In the figure, 1 is a magnetic disk that is a signal recording medium, 24 is a magnetic head that performs magnetic recording on this magnetic disk by its leakage magnetic field, and 3 is a magnetic disk that is a recording medium for signals.
Reference numeral 4 indicates a recording circuit that outputs the recording current of this magnetic head; 4, a recording waveform input terminal that is input to this recording circuit; 5, a recording current supply circuit that controls the amplitude of the recording current of the recording circuit 3; and 6, this recording current. The output of the supply circuit 7 is a unit select signal which is applied in parallel to the recording current supply circuit 5 along with a write enable signal 8, a track address signal 9, an on cylinder signal 10, etc. unit select) signal, 1
1 is a read-only signal generated by the read-only switch 12, 13 is a blocking input terminal of the recording current supply circuit 6 to which the read-only signal is applied, and 14 is a terminal when the terminal B15 of the read-only switch 12 is grounded. The _signal at A16, the read-only signal 11, is connected to the disk controller (see FIG. line driver (line driver (not shown)).
driver).

In the magnetic disk device configured as described above, both the unit select signal 7 and the write enable signal 8 are transmitted from the disk control device, and the unit select signal 8 is a signal for selecting this magnetic disk device. The write enable signal 8 is a signal for performing a recording operation. On the other hand, the track address signal 9 is sent to the magnetic head 2.
is the address information of the truck where is located,
The magnitude of the recording current is changed depending on the positioning track. The on-cylinder signal 10 is a signal indicating that the magnetic head 2 has moved toward a designated track position and has been positioned at that position.

As for the read-only signal 11, when the read-only switch 12 is connected to the terminal B15 side, a high level signal is applied to the blocking input terminal 13 of the recording current supply circuit 5 by the lifting resistor R17 and the power supply _Vc 14, thereby blocking the recording operation. do. When the terminal A16 of the read-only switch 12 is grounded, the read-only signal 11 is at a low level, the blocking input to the recording current supply circuit 5 is released, and the recording operation becomes possible.

However, as mentioned above, unit select signal 7
Since the write enable signal 8 and the read only signal 11 are generated independently, there is a drawback that if the read only switch 12 is erroneously operated during a recording operation, the recording operation is blocked and the recording is interrupted.

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the above-mentioned drawbacks and to provide a magnetic disk device in which even if the read-only switch 12 is operated by mistake, the operation of the read-only switch 12 is postponed until the recording operation is completed. It is something to do.

FIG. 2 is a block diagram showing one embodiment of the present invention, and 1 to 19 indicate the same or corresponding parts as the same reference numerals in FIG. 1 above.

In the figure, 30 is an inverting gate for converting the unit select signal 7 into an inverse theoretical output 31;
2 is a two-input AND gate that receives this inverted gate output and the read-only signal as input, 33 is an OR gate that takes the output 34 of the two-input AND gate 32 as one input, and 35 is the output of this OR gate. is a D type flip-flop with D input, 36 is D
The output of the flip-flop is connected to the blocking input terminal 13 of the recording current supply circuit 5 and the line driver 1.
8 is connected to the gated read-only signal, 37 is a two-input AND gate which receives this gated read-only signal and the unit select signal as input, 38 is the output of this two-input AND gate, and 39 is the above-mentioned D This is the clock signal applied to the flip-flop.

In the magnetic disk device configured as described above, when this magnetic disk device is selected by the disk control device and the unit select signal 7 is at a high level, the output 31 of the inverting gate 30 is at a low level, and the two-input AND Since the output of the gate 32 is at a low level, it has no relation to the output of the OR gate 33. On the other hand, the output of the two-input AND gate 37 has the same logic as the output Q36 of the D-type flip-flop 35, and is again applied to the input D of the D-type flip-flop 35 via the OR gate 33. D
Since the flip-flop 35 is D-type, the second
If the connection is made as shown in the figure, the theory of the output Q of the D-type flip-flop 36 when the unit select signal 7 becomes high level will be maintained. Furthermore, the two-input AND gate 32 is the inverting gate 3
Since the output 31 of 0 is at a low level, it is not changed by the operation of the read-only signal 11 connected to the other input, ie, the read-only switch 12. Therefore, the D-type flip-flop 3
It also has no effect on the logic applied to input D of 5.

Next, when this magnetic disk drive is not selected by the disk controller and the unit select signal 7 is at a low level, the output of the two-input AND gate 37 is always at a low level, and the output Q of the D-type flip-flop 35 is at a low level. Effects are ignored.

Further, the output 31 of the inverting gate 30 becomes high level, and the output of the two-input AND gate 32 is determined by the logic of the read-only signal 11. For example, when the read-only switch 12 is connected to the B terminal 15 side and indicates a read-only state, the read-only signal 11 becomes high level.
The output of the AND gate 32 goes high, and the output of the OR gate 3 goes high and is applied to the input D of the D-type flip-flop 35. When the clock signal 39 is applied at least once, the output Q36
is at a high level. Further, the read-only switch 12 is connected to the A terminal 16 side, and does not indicate a read-only state. In other words, when the recordable state is indicated, the read only signal 1
1 becomes a low level, and the output of the AND gate 32 becomes a low level, but the output of the OR gate 33 also becomes a low level, and the output Q36 of the D-type flip-flop 35 also becomes a low level. As is clear from the above results, when the unit select signal 7 is at a low level, the D-type flip-flop 35 is activated by operating the read-only switch 12.
The output Q36 changes.

To summarize the above explanation, this magnetic disk device is selected by the disk controller,
When the unit select signal 7 is at a high level, the output Q36 of the D-type flip-flop 21, that is, the gated read-only signal 36 does not change due to the operation of the read-only switch 12, and the unit select signal 7 becomes a high level. maintain the state of Therefore, even if the read-only switch 12 is operated during a recording operation, it will not be effective and will not interfere with the recording operation.

Further, when this magnetic disk device is not selected by the disk controller, the unit select signal 7 is at a low level, and the gate read only signal 36 can be changed by operating the read only switch 12. There is no difference from conventional equipment.

FIG. 3 is a block diagram showing a part of another embodiment of the present invention.
Reference numerals 6, 18, 30 to 32, and 37 indicate the same or corresponding parts as the same reference numerals in FIG. 2 above. In the figure, 40 is a flip-flop, 41 is a clock signal applied to this flip-flop, 42 is an output signal of the flip-flop 40, 43 is a flip-flop, 44 is a clock signal applied to this flip-flop, and 45 is an output signal of the flip-flop 43. The unit select signal 7 is applied to the input D ₁ and the synchronized output signal 4 of the flip-flop 40 is applied to the clock signal 41.
2 and a read-only signal 11 to a flip-flop 43 with a clock signal 44 added to input _D2.
This is an example using synchronized output signals. Portions not shown in FIG. 3 are the same as those in FIG. 2 and are therefore omitted.

FIG. 4 is a block wiring diagram showing an example of a partial modification of the embodiment shown in FIG. 2, and numeral 36 designates the same parts as the same reference numerals in FIG. 2 above. Reference numeral 50 denotes a lamp, and the gate read only signal 36 is displayed by the lamp 50 to visually convey it.

As explained above, the present invention is provided with a flip-flop circuit to which a unit select signal and a read-only signal are applied via a logic gate circuit, so that even if a read-only switch is operated during a recording operation, it will not interfere with the recording operation. The effect is that it is possible to obtain a high degree of reliability without any problems.

[Brief explanation of the drawing]

Fig. 1 is a block wiring diagram showing an example of a conventional magnetic disk device, Fig. 2 is a block wiring diagram showing one embodiment of the present invention, and Fig. 3 is a block wiring diagram showing yet another embodiment of the invention. , Figure 4 is the second
FIG. 3 is a block wiring diagram showing an example of a partial modification of the embodiment shown in the figure. In the figure, 1 is a magnetic disk, 2 is a magnetic head, 3 is a recording circuit that outputs a recording current for the magnetic head 2, 5 is a recording current supply circuit, 7 is a unit select signal, 11 is a read only signal, and 12 is a read only switch. , 13 is a blocking input terminal of the recording current supply circuit 5, 32 is a two-input AND gate,
33 is an OR gate, 35 is a D-type flip-flop, 36 is a gated read-only signal, 37
is a two-input AND gate. Note that the same reference numerals in each figure indicate the same or corresponding parts.

Claims (1)

[Scope of Claims] 1. A magnetic disk, a magnetic head that performs recording on the magnetic disk, a recording circuit that outputs a recording current of this magnetic head, a recording current supply circuit that controls the amplitude of the recording current of this recording circuit, and the above-mentioned magnetic disk. A magnetic disk device having a disk control device for controlling the recording operation of the head, and a read-only switch for outputting a read-only signal for controlling the recording current supply circuit and blocking the recording current,
an inversion gate that inverts the logic of the unit select signal output from the disk control device in order to control the magnetic disk to a recording state; an AND gate that receives the output of the inversion gate and the read-only signal; a logic circuit which receives the output of the product gate as an input and outputs a signal at a first logic level when the input is at a first logic level to block the recording current; the output of this logic circuit and the unit select signal; What is claimed is: 1. A magnetic disk device comprising: an OR gate that inputs an AND of the AND gate and an output of the AND gate to the logic circuit. 2. The magnetic disk device according to claim 1, wherein the logic circuit is constructed of a flip-flop.