JPS6180565A - Magnetic disc device - Google Patents

Abstract

PURPOSE:To prevent the missing of data in advance and to improve the reliability of the titled device by providing a write clock signal detecting circuit confirming whether or not a write clock signal is received ahead the write. CONSTITUTION:The read/write clock signal forming circuit 15 of a disc device generates a read/write clock signal in synchronizing with a VFO clock signal and gives it to a disc controller. When the write clock signal detecting circuit 17 receives a write clock signal WC before a write instruction WT, the output of an FF26 is logical 0 and the output AL of an FF27 is logical 0, then no alarm is raised. When the write clock signal WC is not received before a write instruction WT' delayed from a delay circuit 25 is not given with a prescribed time elapsed after the write instruction WT is received, the output of the FF26 is logical 1 and the output AL of the FF27 is logical 1, then the alarm signal is generated and the control circuit 12 processes write inhibition.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic disk device with improved reliability.

Magnetic disk devices have 8 bearer processors compared to magnetic tape devices.
1 is extremely short, and compared to semiconductor storage devices, it has the advantage of being able to permanently store recorded information unless it is rewritten. It occupies a central position as a device.

In addition, as shown in FIG. 2 (al), the magnetic disk device 1
1 is usually connected to a higher-level control device, such as a magnetic disk control device 2, by a command cable 3 and a data cable 4, and writes data on the magnetic disk according to commands given from the magnetic disk control device 2.
Or to read data recorded on a magnetic disk, 5M loading or reading instructions (commands) are sent and received via the command cable 3, and write data and read data are sent and received via the data cable 4. will be carried out.

Note that 11, I2, 13, 14, 15 and I6 are components of the magnetic disk device l, 11 is a driver receiver circuit (D/R circuit) connected to the command cable 3, and 12 is for controlling each part. Control circuit: 13 is a variable frequency oscillator (VFO); 14 is a read/write control I'111 circuit (R/W) that performs read/write IR control;
ib control circuit), 15 is a read/write clock signal generation circuit (R/WC generation circuit) that generates a read/write clock signal, and 16 is a driver receiver circuit (D/R circuit) connected to the data cable 4.

Further, 21, 22, 23, 24 and 25 are components of the magnetic disk control device 2, and 21 is a data cable 4.
22 is a write clock signal generation circuit (WC) that generates a write clock signal.
23 is a write data creation circuit (WD creation circuit) that creates write data.

Reference numeral 24 represents a control circuit for controlling each part, and reference numeral 25 represents a driver receiver circuit (D, /R circuit) connected to the command cable 3.

[Conventional technology]

The reception and reception of write data and read data between the magnetic disk device 1 and the magnetic disk control device 2 is performed using a VFO clock signal generated in a variable frequency, frequency, frequency, and clock circuit 13 built in the magnetic disk device 1. (Figure 2 (
bl time chart ■, the same applies hereafter), but is performed in synchronization with the 5 magnetic disk control devices 21 to exchange read data and write data, or to create write data in the write data creation circuit 23 of the magnetic disk control device 2. In order to do this, it is necessary to receive a clock signal synchronized with the VFO clock signal from the magnetic disk device l side.

Therefore, in the read/write clock signal generation circuit 15 of the magnetic disk device 1, the read/write clock signal ■ is used as a clock signal synchronized with the VF○ clock signal signal.
is created and sent to the magnetic disk controller 2.

In addition, when writing data, write data synchronized with the read/write clock signal ■ sent from the magnetic disk device 1 is created by the write data creation circuit 23 of the magnetic disk control device 2, and along with this write data, the write data necessary for the write operation is generated. Only at this time, the read/write clock signal (2) sent from the magnetic disk device 1 is sent back from the magnetic disk controller 2 to the magnetic disk device 1 as a write clock signal.

It is desirable that the write clock signal (2) sent back to the magnetic disk device 1 maintains synchronization with the VFO clock signal, but in reality, as illustrated in the time chart (2) to (2) of FIG. 2(b), the magnetic Delay tl in the driver of the driver receiver circuit 7g (D/R circuit) 16 of the disk device 1, delay 12 in the data cable 4. Delay tLJ l in the receiver of the driver receiver circuit 21 of the magnetic disk control device 2 and inside the magnetic disk control device 2 Delay t4 in the driver of the driver receiver circuit 21 of the magnetic disk control device 2. Additionally, a delay 5 occurs in the receiver of the driver receiver circuit 16 of the magnetic disk device 1.

For this reason, create clock signals A and B in the read/write clock signal creation circuit, and (4
The read/write control circuit 14 of the 1st disk drive 1 is designed to correctly capture the interrogation data (2).

By retaking the write data ■ sent in synchronization with the trailing edge of the rewrite clock signal ■ at the leading edge of the write clock signal ■, write data ■'' is created. In order to synchronize the clock and the write data ■', the receiver compares the phase difference between the received write clock signal ■ and the VFO clock signal ■, and determines whether the leading edge of the write clock signal ■ is the VFO clock signal ■.
When the clock signal A matches the “0” level of
Furthermore, if the leading edge of the write clock signal ■ matches the "1" level of the VFO clock signal ■, the clock signal B
Take the write data ■ and create write data ■ using .

The reason why the write data ■ is re-incorporated into ■° and from ■1 to ■ is because the total time T of the delay times t1, L2...t5 is uncertain due to cable length and element variations, etc. .

Write data synchronized with the VFO clock ■.

After that, it is sent to the modulation circuit inside the R/W control circuit 14.

[Problems to be Solved by the Invention] In the device having the above configuration, the write clock signal ■ may be interrupted by the read/write command of the magnetic disk device 1 due to a failure in the internal circuit of the magnetic disk control device 2 and the driver side of the driver/receiver circuit 21. If the control circuit 14 is not reached, the write data (2) cannot be read again at the leading edge of the write clock (2), so there is a problem that the write data (2) cannot be written correctly.

[Means for solving problems]

A magnetic disk device according to the present invention is a magnetic disk device that writes data sent from a host control device in response to a write command sent from the host control device.
By providing a write clock signal detection circuit for checking whether or not a write clock signal is being received prior to writing.

This is an attempt to solve the above problem.

[Effect]

In other words, in the present invention, prior to writing, it is checked whether or not a clock signal is being received from the host control device, and if the clock signal is not being received, an alarm signal is generated and writing is not performed. It is something.

〔Example〕

The gist of the present invention will be specifically explained below with reference to an embodiment shown in FIG.

FIG. 1 ra+ is a block diagram showing the configuration of an embodiment of the present invention, and FIG.
C detection circuit).

FIG. 1B shows a specific configuration example of the write clock signal detection circuit 17, and reference numeral 25 denotes if, which delays the write command WT given from the control circuit 12 by a predetermined time.
26 is a D-type flip-flop set by the first leading edge of the write clock signal C; 27 is a negative FU of the flip-flop 26;
The output of the delay circuit 25 takes the output of the ll terminal Q as an input, and the output WT'
It is a D-shaped flip-flop set by .

In addition, FIG. 1 (C1 is a time chart explaining the operation of the above embodiment, WC is the same write clock signal as in FIG. 2 (BL), WT is a write command given from the control circuit 12, IQ is a flip-flop WT' is the write command delayed by the delay circuit 25, and AL is the alarm signal output from the flip-flop 27.

As shown by the solid line, if the write clock signal -0 is received before the write command WT.

The output of flip-flop 26 is "0", and therefore the output of flip-flop 27 is "0", ie, no alarm signal is generated.

Further, as shown by the dotted line, if a predetermined time has elapsed since the write command was received and the write clock signal WC is not received from the delay circuit 25 when the delayed write-in command penalty is issued. , the output of the flip-flop 26 is "l"
"l, so the output of flip-flop 270 and "1'
That is, an alarm signal is generated, and the control circuit 12 takes action to inhibit writing.

(Effects of the Invention) As explained above, according to the present invention, the loss of data generated by writing without using a writing clock signal can be prevented, and the reliability of the magnetic disk device can be improved. It has the effect of

[Brief explanation of drawings]

Figure 1 (al is a block diagram showing the configuration of an embodiment of the present invention. Figure 1 (b) is a specific configuration example of the main part of the embodiment. Figure 1 tc+ explains the operation of the embodiment. Time chart. Figure 2 (ta) is a circuit diagram of a conventional example. FIG. 2 (BL is a time chart explaining the problems of the conventional example. In the figure. ■ is a magnetic disk device. 2 is a magnetic disk control device. X7 is a write clock signal detection circuit. 25 is a delay circuit. 26 and 27 are flip-flops.

Claims (1)

[Claims] In a magnetic disk device that writes data sent from a host control device in response to a write command sent from the host control device, write clock signal detection is performed to check whether or not a write clock signal is received prior to writing. A magnetic disk device characterized by being provided with a circuit.