JPS60246066A - Diagnosis system of reading circuit - Google Patents

Abstract

PURPOSE:To assuredly actuate a reading circuit even though the write data is used as it is as the read data and to diagnose surely the reading circuit, by switching a device to a read state from a write state after holding temporarily the demodulated data at a buffer within a reading circuit and checking error detecting/correction action. CONSTITUTION:In a write mode, the data is fetched in a channel buffer 2 via an interface 1. An error code is added by an ECC generating circuit, and the code is converted by a 4-5 conversion circuit 5 and written to a magnetic tape via a modulation circuit 6 and an MTU interface 7. In a read mode, a demodulation circuit 9 demodulates the data based on a reference pulse fed from a VFO10. Then the error detected and corrected by an error detection circuit 12 and an errorcorrection circuit 13 via a skew correction circuit 19 and a 5-4 conversion circuit 11. The result is stored temporarily in the buffer 2, then read out to be transferred to an upper device via the interface 1.

Description

[Detailed description of the invention]

[Field of Application of the Invention] The present invention relates to a diagnosing method for a reading circuit, and more particularly to a diagnosing method for a reading circuit that uses a signal obtained by demodulating written data to diagnose a reading circuit that performs error detection and correction. [Background of the Invention] In order to maintain the reliability of data in devices constituting a computer system, such as magnetic tape devices, magnetic disk devices, main memory devices, etc., CRC (Cyclic Redundancy Check) is used.
dancy Check) and ECC (Error
CorrecLion Code) etc. are added to the data. Therefore, in the reading circuit, it is important to check whether the error detection/correction function using CRC or FCC is operating normally at all times in order to ensure data reliability. For example, in a magnetic tape control device, in order to diagnose the reading circuit, intentionally erroneous data is detected and detected.
A method has been proposed for diagnosing whether the circuit is normal or not based on the output of the correction circuit (1).
(See Publication No. 2162). In this method, as shown in FIG. 1, in order to diagnose the error detection/correction circuit 40, an arbitrary FCC code is transferred in advance from the maintenance panel 31 to the ECC buffer 32 in addition to the write data. When writing to a magnetic tape, data is transferred from the write buffer 2 to the modulation circuit 2G via the selector 3, but for ECC, the FC
Instead of the code from the C generation circuit 4, the code (-) from the FCC buffer 32 is sent to the modulation circuit 6 via the selector 33.3.
Transferred to As a result, it is possible to create data errors virtually, and the error detection/correction circuit 3
9 given to 4. The error detection/correction circuit 3/1 outputs to the diagnostic circuit 35 whether or not there is an error in the data, whether or not the error can be corrected, and the corrected data. At the same time, a correctable error signal is transmitted via signal lines 36 and 37;
An uncorrectable error signal is output. The diagnostic circuit 35 checks from these signals and the output of the selector 3 whether or not the error detection/correction circuit 34 has functioned normally. However, in the method shown in Figure 1, since the data once written on the magnetic tape and the FCC are input to the reading circuit, there is an influence from parts such as the recording/playback head and the recording medium, making accurate diagnosis impossible. There are drawbacks. Therefore, in the conventional magnetic tape control + J device,
As a method for diagnosing a reading circuit, a method is used in which write data is used as input data and the reading circuit is manually operated directly. For this reason, a path is set up inside the control device that uses write data as read data.

[I am writing. However, this method also has the following problems. (1) The write data modulation circuit of the magnetic tape control device performs modulation taking into consideration the characteristics of the write head, the recording medium, etc., in order to obtain the optimum data waveform for the recording medium. Therefore, if this modulated data is input directly to the reading circuit without going through a recording medium, a phase error may be detected, and therefore it is difficult to operate the reading circuit stably. I can't. (11) A magnetic tape control device normally operates in either a writing or reading state. Therefore, when writing data is directly input to the reading circuit, the device must be operated in the writing state.
Only the parts of the reading circuit that operate in the activated state can be diagnosed. [Objective of the Invention] The object of the present invention is to improve such conventional problems, and even if written data is used as it is as a read tape,
It is an object of the present invention to provide a diagnostic method for a reading circuit that can operate the reading circuit reliably and perform diagnosis in the original operating state of the reading circuit. [Summary of the Invention] In order to achieve the second object, the reading circuit diagnostic method according to the present invention inputs modulated write data as input data to the reading circuit, demodulates the data, and then performs error detection and correction. A diagnostic method for performing an operation and checking the operation includes means for changing a modulation method of written data, and a control means for switching the means to operate only during diagnosis, and under the control of the control means, demodulated data is The apparatus is characterized in that after temporarily holding the tape in a buffer in the reading circuit, the apparatus is switched from the writing state to the reading state, and the error detection 11 and correction operations are checked. [Embodiments of the Invention] Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 2 is a block diagram of a magnetic tape control device showing one embodiment of the present invention. In Fig. 2, instructions from the MicroProsen-IJ1/I indicate that when modulating write data during diagnosis, phase correction is not performed due to the characteristics of the head or recording medium, and that the readout circuit is By using the buffer 19 for skew correction between the trunks and temporarily storing the read data there, it is possible to reliably diagnose the read circuit without adding or changing any hardware. I did it like that. First, in a normal write state, the tape given from the channel is taken into the channel buffer 2 via the channel interface 1.
．． Next, in synchronization with the operations of the write circuits 3 to 6, the data is read from the channel buffer 2, an error correction code generated by the FCC generation circuit 4 is added to the data, and 'l-5 conversion is performed. Transfer to circuit 5. The 4-5 conversion circuit 5 converts the sign of the input data and then outputs it to the modulation circuit 6. The modulation circuit 6 modulates this data, transfers it to the magnetic tape device via the MTU interface 7, and writes the data onto the tape with the magnetic tape device. Next, in a normal reading state, data read from the magnetic tape is input to the magnetic tape controller via the MTT, J interface 7. A demodulation circuit 9 demodulates input data based on a reference pulse generated by a VFO (variable frequency oscillator) 10. Skew correction circuit] Transfer to 9. Skew correction circuit 1
9 corrects the skew between each track with respect to the input data, and sends it to the 5-4 conversion circuit 11. The 5-4 conversion circuit 11 performs code conversion on the corrected data and sends it to the error detection circuit 12 and error correction circuit 13. Data whose errors have been detected and corrected by the error detection circuit 12 and the error correction circuit 13 is transferred to the channel buffer 2 and temporarily stored therein. The data written to the channel buffer 2 is then read out and transferred to the host device via the channel interface 1. In addition, in the above-mentioned deep writing state, immediately after writing data, it is confirmed that the writing was performed normally. In other words, the data written on the recording medium during the write operation is read out, demodulated, converted, and error corrected in almost the same manner as in the read state, and during that time it is confirmed that the read data is error-free. Check things out. In Figure 2, G CR of 625.0 RPT, (G ro
UP (joded recording) method is used, and an FCC of 1 pie 1 to 1 is added to 7 bytes of data, making it possible to correct errors that occur simultaneously over 21 racks. During writing, the 4-5 conversion circuit 5 converts 4-bit data into 5-bit data, and the modulation circuit 6 converts the data to 5-bit 1 into NR7.
,I (Non Return to Zero Ch.
anBeonOnes) method and sends it to a magnetic tape device. At the time of reading, conversely, the NR and ZT methods are demodulated and 5-bit 1- is converted into 4-bit data. Next, when diagnosing the reading circuit, the microprocessor 1/
Perform self-diagnosis within the magnetic tape control device using
First, the microprocessor 14 sends data for nast for diagnosing the reading circuit to the circuits 9 to 18 constituting the reading circuit (18.19). - Write to buffer 2. Microprocessor 14 is connected to each selector 3, 8 and each circuit 1 to 19 via a plurality of instruction lines 15, and these circuits can be operated arbitrarily by progera 11. The microprocessor 14 first controls the selector 8 via one of the instruction lines 15 and switches it so that the write data 16 can be input as read data. puts each circuit in the write state via the circuit and instructs the circuits 3 to 6 to operate.As a result, the test data written in the channel buffer 2 is read out, and the 4-5 conversion circuit 5 and the modulation circuit 6 line 1 as write data via
6 is output. FIG. 3 is a block diagram of the modulation circuit of FIG. 2. In the 1'6= modulation circuit, phase shifts due to writing/\tsu1- and the characteristics of the recording medium are taken into consideration. Phase correction is being performed. Therefore, if a normal modulation circuit is used as it is as the modulation circuit 6 in FIG.
, which can lead to phase errors. Therefore, in this embodiment, as shown in FIG.
A selector 20 is provided within the microprocessor 14, and an instruction line 15 from the microprocessor 14 is used to prevent the above-mentioned phase correction from being performed. That is, the selector 20 selects the output of the modulation section 2j in the modulation circuit 6 and the output of the phase F+Ii positive part 2:3.
Allows you to switch and select arbitrarily. Normally, the output of the phase correction unit 2; 3 is selected and the microprocessor]/I
It is only necessary to set the output of the modulation section 21 to be selected only when an instruction is received from the instruction line 15 from the instruction line 15. As a result, during normal writing, data corrected by the phase correction unit 23 is sent to the magnetic tape device, and during self-diagnosis, that is, when inputting line 16 directly to the demodulation circuit 9, data that has not been phase corrected is sent to the magnetic tape device. Since the reading circuit is used for diagnosis, it is possible to reliably diagnose the reading circuit. The test data input to the demodulation circuit 9 from the line 16 is demodulated using VFOIO, and the skew correction circuit]
9 corrects the skew between each track, and further 5
After the data is code-converted by the -4 conversion circuit 11, the error detection circuit 12 and the CRC check circuit 18 check whether there is an error in the data. During this time, the microprocessor 14 needs to control the writing, but since the data transfer speed by the circuits 9 to 13, 18 and 19 is faster than the processing speed of the microprocessor 14, the data is not output from the error correction circuit 13. It is not possible to directly test the content of the data. Therefore, after the write process is completed, the microprocessor 14 receives the results of the error detection circuit 12 and the CRC check circuit 18 via the instruction line 15, checks this, and if there is no error in the data, the read circuit is activated. Circuit 9 to +3
．． 18. Confirm that 19 is working properly. Furthermore, the microprocessor 14 causes the data on the line 16 to output data containing an error as shown in the figure in the same manner as the above operation, so that the error detection circuit 12 and the error correction circuit 13 operate normally and the error is detected. is detected and corrected. Outputting erroneous data on line 16 can be easily achieved by the method shown in FIG. FIG. 4 is a block diagram of the skew correction circuit in FIG. 2. In order to correct the skew between each rack, the skew correction circuit 19 has internal components for each rack, as shown in FIG.
Memory 22 for temporarily holding data for each rack
It is equipped with Note that in FIG. 4, only the memories 22 corresponding to racks 0 and 1 are shown;
The memory corresponding to No. 8 and the control circuit for skew correction which are not directly related to the present invention are not shown. For diagnosis up to 29, 'i!' of the reading circuit! Since only the portion that operates in the F-reading state can be diagnosed, in this embodiment, the data is temporarily stored in the skew correction circuit 19 and then switched to the reading state. That is, when a diagnostic operation is performed in the above-mentioned write state, note that the Nast data is written in the memory 22 of the skew correction circuit 6, and use this.
The microprocessor I4 sends an instruction to each circuit in the device via the instruction line 15 to interrupt the operation when the data for dest is written in the memory 22. Microprocessor 1/1 then changes device 2 from the write state to the read state. Instructs circuits 11 to 13.18 and 19.2 to perform a read operation. As a result, the dest data written in the memory 22 is read out to the 5-/I conversion circuit 11 and code-converted, an error is detected by the error detection circuit 12, and the data is passed through the error correction circuit 13. The data is checked by the CR, C check circuit 18 and finally written to the channel buffer 2. The microprocessor 1/l operates in the same manner as in the sacrificial state, and after the operation is completed, the error detection circuit 1
2 and the check results of the CRC check circuit 18, and the contents of the channel buffer 2 are transferred to the bus line 1.
Find out via 7. This confirms the correctness of the written data. By checking the data content during the reading state, the above! The reading circuit (circuit 11 to +3.18°1
9.2) can be tested. Also, in the operation in the read state, data containing an error is outputted to the line 16, written in the memory 22, and the error detection circuit 12 in the read state is outputted in the same manner as in the write state. The operation of the correction circuit 13 is tested. In this way, the microprocessor 14 can arbitrarily change whether or not to perform phase correction on the write data. Using this data, the reading circuit can operate stably, and the memory 2 in the skew correction circuit 19
Because data is temporarily stored in 2. 11 After changing the device from the reading state to the reading state,
Regarding the diagnosis of the microprocessor, the microprocessor is switched to the diagnostic mode by the error detection signal from the error detection circuit, and the microprocessor is operated at low speed under the control of this microprocessor. [A method of performing diagnosis using 1 gram (see Japanese Patent Laid-Open No. 57-481/lli;; Publication) has been proposed. In this embodiment, since data is stored in the memory 22, when operating in the read state, the above method can be used to synchronize each circuit making up the read circuit with the microprocessor I4. 1. This makes it possible to operate the microprocessor 4 in the case where there is a large difference in operating speed between the microprocessor 4 and the reading circuit.
Diagnosis can be easily performed even with a low-speed microprocessor. Moreover, at the same time, the microprocessor 14 can check the data directly obtained on the output line 23 without going through the channel buffer 2 even during operation in the reading state. Also helpful. [Effects of the Invention] As described above, according to the present invention, even if write data is used as read data, the read circuit can operate stably, so the read circuit can be reliably diagnosed. Additionally, by temporarily storing read data in memory, the device can be operated from a write state to a read state, which improves diagnostic functionality.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a diagnosis method of a conventional magnetic tape control device, FIG. 2 is a block diagram of a magnetic tape control device showing an embodiment of the present invention, and FIG. 3 is an internal block diagram of the modulation circuit shown in FIG. 2. 4 are block diagrams of the skew correction circuit of FIG. 2. 1: Channel interface, 2: Channel buffer, 6: Modulation circuit, 3.8, 20: Selector, 9: Demodulation circuit, 12: Error detection circuit, 13: Error correction circuit, 14
:Microprocessor→J, ]9 Niskew compensation circuit, 2
1: Modulation section, 22: Memory, 23: Phase correction section. Fold No. 6 Figure 1! :I Figure 4 ・ 1 1゛I J

Claims (1)

[Claims] (1) A method for modulating write data in a diagnostic method that inputs modulated write data as input data to a reading circuit, demodulates the data, performs error detection and correction operations, and performs an operation check. and a control means that switches and operates the means only during diagnosis. Under the control of the control means, the demodulated data is temporarily held in a buffer in the reading circuit, and then the device is read from the write state. A diagnostic method for a reading circuit characterized by switching the state and checking error detection/correction operations.