JPH0277660A - Method for judging medium fault of magnetic disk evaluating device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a medium defect determination processing method in a magnetic disk medium evaluation device. The means for determining medium defects is configured by a hardware circuit.

[Prior Art] In magnetic disks used for recording information, some kind of defect occurs in the magnetic medium during the manufacturing process, causing errors in recorded information. Such magnetic media are inspected for defects by performing a medium inspection (certify) using a magnetic disk evaluation device and detecting errors occurring in test codes.

Figures 2(a) and 2(b) explain errors that occur in test codes during media inspection and their inspection methods.
In a), a large number of trunks TR set on the magnetic disk 1 are equally divided into a plurality of sectors 81 to SS in the circumferential direction, and the sectors of each track are divided as shown in (a) of FIG. A test code is written. When this is read, as shown in (a), a pulse Pe1 larger than the standard level Lo or a pulse Ne smaller than the standard level Lo appear mixedly.

These are compared with a certain threshold LP, and a large pulse group is determined to be a positive (Pe) error, and compared to a threshold value LN, a small pulse group is determined to be a negative (Ne) error. M in the figure is a mincing error in which pulses are missing. In addition, (c) shows an emerging error (extra error) E detected by reading from a disk on which recording has been erased.

These various code errors include inherent flaws in the medium itself (
In addition to those caused by defects in media (medium defects), these include those caused by things other than the medium, such as attached dust. In order to evaluate the medium based on the detected error data and feed it back to the disk manufacturing process, it is necessary to exclude defects caused by defects other than the medium and obtain data only about medium defects. Therefore,
If the reading is retried multiple times and the number of occurrences is small,
It is assumed that the dust that causes the error has moved or dispersed during the retry and is not detected again, or that it has entered the truck midway and was detected, and is excluded from the data.
A method is used in which a medium is determined to be defective if it is detected more than a certain number of times.

The most basic method for inspecting media defects in 1. above is to rotate the disk and, when an error is detected in the test code read out, store the sector number of the error in a small memory such as a register. In this method, the presence or absence of an error is checked at the position of the sector by the next rotation, the rotation is repeated the necessary number of times, and the number of errors in each rotation is totaled.
It is clear that in the case of a large number of errors, the efficiency is very low. Therefore, a method is used in which all errors in each sector detected in each rotation are stored in a memory, and medium defects are determined by processing by a microprocessor.

Fig. 3 explains a method for determining medium defects by recording error data from multiple reading attempts using memory and processing by a microprocessor. The type is identified by the type identification circuit and recorded in the error memory 2 by processing by the microprocessor. The error memory 2 has N memory areas 2-1, 2-2, . . . corresponding to each number of readings.・・・
・2-N is provided, and in each memory area, the sector number (
SNo) and a code (Kcod) representing the type. In this case, errors of the same type existing in the same sector are stored as one regardless of the number. For the errors stored in each memory space, the total number n for each type and each sector and the ratio n/N of the number n to the number of retries N are determined. If n/N is larger than a certain reference value n□/N, it is assumed that there is a medium defect. Furthermore, when n/N is less than no/H, it is excluded as being caused by a defect other than the medium.

For example, the number of retries N is 5 and the reference value is 215 (no
= 2), if the error is detected around 2 times, it is a medium defect, and if it is detected only once, it is determined to be something other than the medium. The above processing is performed for each track, and the medium defect data is displayed or printed out in the order of sector numbers by processing by a microprocessor, with a defect type code attached.

[Problem to be Solved] The above-mentioned recording of detected error data in a memory space, calculation of their total, and medium defect determination processing are all performed by a microprocessor program. However, in recent large magnetic disks, the recording density and capacity are enormous, and the number of defects has increased proportionally. It takes a considerable amount of time to import the data into the processor and compare and match it. On the other hand, since the recording or calculation processing for the memory in this case is extremely simple, it is considered faster and more advantageous to perform the processing using a hardware circuit.

This invention was made in view of the above-■-, and it records detected errors in a memory space by a hardware circuit, not by a microprocessor program, and determines whether the error data is due to a defect specific to the medium. The purpose of this project is to provide a medium defect determination processing method that quickly determines whether the defect is caused by something other than the medium, such as dust, by comparing it with the above reference value, and records the collected results in a defect memory. be.

[Means for Solving the Problems] The present invention is a medium defect determination processing method in a magnetic medium evaluation test in which a test code written in each sector of a track of a magnetic disk is read a plurality of N times. Then, the error that occurs in the test code in each of the N number of reads and whose type is identified by the error type identification circuit is stored in the memory space for the type at an address corresponding to the sector number and number of reads of the error. The error writing means, which becomes old as one error bit, and the number of error detections for a plurality of N times of reading for each type and sector of error data in the memory space are calculated in total by 3f.
L, a determining means for determining that an error is due to a medium defect when the ratio n/N of the total number n to a plurality of N is less than a reference value n□/N; and a medium defect determined by the determining means. A control means for writing the sector number and defect type for the defective memory into the defective memory is configured by a hard circuit.

[Operation] In the medium defect determination processing method of the magnetic disk evaluation device of the present invention having the above configuration, a test code error detected during reading is sent to the address of the corresponding sector number and number of times in the memory space for each type. It is stored in one bit, and when multiple attempts are completed, the number of error detections for multiple N times is totaled for each sector in the medium defect determination circuit, and the total number n and the ratio n/n for multiple N times are calculated.
N is calculated, and this value is compared with a certain reference value no/H, and when it is greater than that, it is determined that the media is defective. Based on this determination result, the sector number in which the medium defect exists and the error (defect) type are recorded in the defective memory in sector order by the write-in control circuit, and are printed out. All of the above-mentioned recording processing for the error memory, calculation of the number of error detections, recording for the defective memory, etc. are quickly performed by each circuit having a hardware configuration. In addition,
The reference value n□/N is set according to actual circumstances.

[Embodiment] FIGS. 1(a), (b), and (e) are explanatory diagrams of the block configuration and determination processing in an embodiment of the medium defect determination method of the magnetic disk evaluation apparatus according to the present invention. Figure (a
), a test code is written into the track of the magnetic disk 1 by the magnetic head 3 for each sector. The signal of the read test code is adjusted to an appropriate level by the amplifier 4, inputted to the error type identification circuit 5, where the error type is identified. This error bit is representatively displayed. Such identification and bit processing are conventional methods. - On the other hand, the sector mark provided between the test codes read out sequentially is counted by the sector counter 5a and the sector number is changed.

The sector number and error type code for the error bit obtained above are written into the error memory 7 by the error write circuit 6. The error memory 7 is stored in the error memory 7 as shown in FIG.
) from the first memory area 7-1 for positive (Pe) errors, the second memory area Fu 2 for negative (Ne) errors, and the third memory area Fu 3 common to missing errors M and extra errors E. Become. Also,
As shown in Figure (b), each memory area has a sector number (SNo) in the horizontal direction of the address, and a read count (SNo) in the vertical direction.
N), and one bit is recorded at the address of the sector number where the error bit was detected.

The number of successive reads is counted by the error write circuit, and an address corresponding to the number of times is specified, and l- writes are performed.

Next, the error data of each memory area is transferred to the medium defect determination circuit 8, and the total number n of error detections for N readings for each sector number and the ratio n/N for the plural number N are calculated. This is the preset reference value n(1
/N, and by the method described above, n/N is compared to no/N.
If the number is N or more, it is determined that the error is due to a medium defect. Here, the reference value no/N can be changed arbitrarily and is set according to the actual situation. Next, the sector number and defect type code for the medium defect are recorded in the defect memory 10 by the defect write control circuit 9. defective memory 10
As shown in Figure (C), the sector number (SNo) and defect type (Pe, Ne, M/E) are indicated by flags. Here, the sector number recorded in the defective memory is determined by the number of times the medium defect determination circuit 8 processes the address counter 8a.
It can be counted by

Note that extra error E cannot be detected at the same time as the above readout, so the same readout as above is performed after erasing the test code. The above-described reading and determination processing is sequentially performed for each track to evaluate the entire disc.

[Effects of the Invention] As is clear from the above explanation, in the medium defect determination method of the magnetic disk evaluation device according to the present invention, each circuit of the hardware structure detects an error in response to an error in a test code that has been read out multiple times. This method involves recording to memory, determining the recorded error data, and recording the determination results to the defective memory.It is much faster than conventional program-based processing methods, and uses high-density, large-capacity magnetic The effect of being able to complete evaluation tests on disks in a short time is significant.

[Brief explanation of the drawing]

FIGS. 1(a), (b), and (C) are explanatory diagrams of the block configuration, error memory, and defective memory in an embodiment of the medium defect determination method of the magnetic disk evaluation apparatus according to the present invention, and FIG. 2(a) and (b) are explanatory diagrams of test code errors that occur on magnetic disks and their inspection methods, and Fig. 3 is an explanatory diagram of the conventional medium defect determination method for Figs. 2 (a) and (b). . 1...Magnetic disk, 2...Error memory,
3... Magnetic head, 4... Old/read amplifier, 5... Error type identification circuit, 5a... Sector counter, 6... Error 3-inclusive circuit, 7... Error memory, ? -1... First memory area, 7-2... Second memory area, 7-3... Third memory area, 8... Medium defect determination circuit, 8a... Address counter, 9... ...Defective write control circuit, 10... Defective memory.

Claims (1)

[Claims] In an evaluation test of a magnetic medium in which a test code written in each sector of a track of a magnetic disk is read a plurality of N times, an error occurs in the test code in each of the plurality of N times of reading, and an error type identification circuit an error writing means for writing an error whose type is identified by a 1-bit error bit into an address corresponding to the sector number and read count of the error in a memory area for the type; Then, for each type and sector, the number of error detections for the plurality of N readings is totaled, and when the ratio n/N of the total number n to the plurality N is equal to or greater than a reference value no/N,
A determination means for determining that the error is caused by a defect inherent in the medium (hereinafter referred to as a medium defect), and a control means for writing the sector number and defect type for the medium defect determined by the determination means into the defect memory are provided in a hard circuit. A medium defect determination processing method for a magnetic disk evaluation device, characterized in that it is configured by: