JPH10172244A - Data memory apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize data reading and writing operation without reduction of processing speed even with simplified structure even if default region is generated. SOLUTION: During writing operation of the image data GD, a defect region of a hard disc 23 is detected, and it is stored in a defect table 24. In the defect region, writing of the image data GD is suspended and the remaining part of image data GD is written from the adjacent sector. At the time of reading the image data GD, the data read during the defect region period controls the data transmission of FIFO 21 and SCSI controller 22 for exception from the image data GD by referring to the defect table 24. Therefore, a pseudo acknowledgment signal ack' is generated by using a match control signal CS in order to stop the transmission of data to FIFO 21.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data storage device suitable for storing image data.

[0002]

2. Description of the Related Art As an image memory of a printing apparatus, a random access memory has been widely used. However, in order to cope with high resolution and high gradation of the printing apparatus or printing of a plurality of copies, a random access memory has been used. The use of a so-called secondary storage device is being considered. The magnetic hard disk device has an advantage that the unit price per memory size is low, but on the other hand, it has a disadvantage that it is not suitable for real-time processing because the reading speed cannot be guaranteed.

[0003] For this reason, the following techniques have been developed in order to solve such disadvantages. First, JP-A-5-130344
Japanese Patent Application Laid-Open Publication No. H11-163873 discloses a technology that eliminates the need for a buffer memory by setting the processing speed of a secondary storage device to be the highest among the processing speeds of each part of the device. Next, JP-A-7-
Japanese Patent Application Laid-Open No. 61057 discloses a technique for processing image data in real time when an error occurs when image data is read from a secondary storage device, by interpolating and outputting the line in which the error exists by the preceding and following lines. Have been. Next, Japanese Patent Application Laid-Open No. Hei 7-244727 discloses a technique for temporarily storing image data read from a secondary storage device in a page buffer and starting printing after reading is completed, thereby guaranteeing image output. It has been disclosed.

[0004]

Incidentally, in a secondary storage device such as a magnetic hard disk device, a defect of a magnetic material may occur while the secondary storage device is being used, and a specific area may not be read or written. This area is called a defect area, and usually exists at several places to several tens places in one device. In many recent hard disk devices, a certain storage area is reserved as an alternative area in advance, assuming that a defect area exists. This replacement area is provided, for example, on the innermost circumference of the disc. Here, it is assumed that sector n is a defect area when data is written in sector 0, sector 1,... Sector n. In this case, data is continuously written between sector 0 and sector n-1, and when sector n is reached, data writing is interrupted, the head is moved to an alternative area, and data writing is resumed. When the data writing to the alternative area is completed, the head is moved again and the data writing is restarted from sector n + 1. In this case, it takes time (seek time) to move the head. That is, the data write speed and the data read speed vary depending on the presence of the defect area.

Therefore, in practice, the data writing speed and the data reading speed fluctuate.
When the technology described in Japanese Patent No. 30344 is adopted, there is a problem that reading and writing of data to the magnetic hard disk device cannot be performed in time, and a part of image data is lost.

Further, in the technique described in Japanese Patent Application Laid-Open No. 7-61057, the image quality is deteriorated due to interpolation in a line. For example, if a thin line represented by one line corresponds to the default area, the thin line disappears due to interpolation of the preceding and following lines.

In the technique described in Japanese Patent Application Laid-Open No. Hei 7-244727, since image data is temporarily stored in a page buffer, a long time is required for processing. In particular, even when the storage area to be read from the magnetic hard disk device does not include the default area, the output cannot be performed until image data is accumulated in the page buffer, so that the time efficiency is low.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and has a simple configuration so that even if a defect occurs during use, data can be read and written without reducing the processing speed. It is an object to provide a storage device.

[0009]

According to the first aspect of the present invention, there is provided a storage unit for storing data, a writing unit for writing the data in the storage unit, and a normal unit. Defective area management means for storing a position of a defective area where writing is not possible; and controlling the writing means so as to stop writing of the data when the defective area occurs during the data writing period. Write control for controlling the position of the defective area to be stored in the defective area management means and controlling the writing means to restart writing of the data from an area adjacent to the defective area Means.

[0010] In the invention according to claim 2,
Storage means for storing data; defective area management means for storing the position of a defective area where normal writing is not possible; reading means for reading the data from the storage means; and Data generating means for recognizing the position of the defective area and generating output data by excluding data from the defective area out of the data read by the reading means.

It is to be noted that these specific features of the invention include writing means for writing the data in the storage means, and writing of the data is stopped when the defective area occurs during the data writing period. And controlling the writing means to store the position of the defective area in the defective area management means, and restarting the writing of the data from an area adjacent to the defective area. Writing control means for controlling the means (claim 3).

Further, in the invention according to claim 4,
The reading means generates a request signal instructing a transmission request in synchronization with the read data, and after receiving an acknowledgment signal instructing reception confirmation from the data generating means, outputs the next data, and outputs the next data. The generating means is
Specifying means for specifying a defective area read period for reading the data of the defective area with reference to the defective area management means; and interrupting means for interrupting data fetching from the read means during the defective area read period; A pseudo acknowledgment signal generating means for generating a pseudo acknowledgment signal equivalent to the acknowledgment signal during the defective area reading period, and a transmitting means for transmitting the pseudo acknowledgment signal to the reading means.

[0013] The specifying means obtains the read position by specifying the current read position by measuring the request signal, and obtains the specified current read position and the defective area management means. The apparatus may further include a determination unit that compares the position of the defective area and determines a period in which the two coincide with each other as the defective reading period (claim 5). Further, the pseudo acknowledgment signal generating means may generate the pseudo acknowledgment signal based on the request signal output from the reading means (claim 6). Further, the defective area management means may be formed inside the storage means.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION

1. 1. Configuration of Embodiment 1-1: Overall Configuration Hereinafter, an image forming apparatus using a data storage device according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram of the image forming apparatus. In the figure, 1
Is a control unit, which is connected to each component via a bus b and controls the entire image forming apparatus. Reference numeral 2 denotes a secondary storage device in which a large amount of image data GD is stored.
Is stored. Here, the image data GD is expressed in bitmap data or an intermediate language. A printer engine 3 prints an image formed based on the image data GD on a sheet. Reference numeral 4 denotes an image data transmission unit, which functions as an interface for supplying image data GD transferred from the control unit 1 or the secondary storage device 2 to the printer engine unit 3. For example, if the printer engine unit 3 prints an image while sequentially scanning each line, the image data sending unit 3 supplies the image data GD to the printer engine unit 3 in synchronization with the scan. Reference numeral 5 denotes a network controller, which is connected to a plurality of personal computers (not shown) via a LAN (local area network), thereby sharing the image forming apparatus.

1-2: Configuration of Control Unit 1 Next, the configuration of the control unit 1 will be described. Reference numeral 10 denotes a CPU, which controls the entire apparatus such as writing / reading of the image data GD to / from the secondary storage device 2 or transfer of the image data GD to the image data transmitting section 4. Reference numeral 11 denotes a cache memory, which functions as a work area of the CPU 10. A bus bridge 12 connects the bus a and the bus b to each other. Reference numeral 13 denotes a main memory which stores image data GD and stores image data GD therein.
A management table TB for managing reading of D is stored.

FIG. 2 shows the contents of the management table TB. As illustrated, the management table TB includes a set of a page number PN, a start address SA, a data size DS, and a defect number DN. Here, the start address SA indicates the head sector of the storage area in which the page is stored, the data size DS indicates the data capacity of the page, and the number of defects DN stores the page. The number of defect locations in the storage area is indicated in sector units. Since the number Y of data stored in each sector is known in advance, the number X of sectors in the storage area where a certain page is stored can be calculated by the following equation. X = DN + DS / Y

Reference numeral 14 denotes a data buffer LSI, which functions as a buffer for adjusting timing when transmitting image data GD.

1-3: Configuration of Secondary Storage Device 2 Next, the configuration of the secondary storage device 2 will be described. Reference numeral 20 denotes a bus control unit connected to the bus b, which controls the transfer of commands from the CPU 10 and the transmission of image data GD to the bus b. A FIFO 21 is a memory that outputs data in the order of data input, and adjusts timing.

Reference numeral 22 denotes a SCSI controller;
Is a hard disk. Hard disk 23 is SCS
It is managed by the I-controller 22 and stores a large amount of image data GD. Further, the hard disk 23 can issue a mode select command at the time of initialization such as power-on or reset, and set a mode relating to error reporting. In this example, it is set so that an error is reported immediately when an error occurs at the time of writing, and an error is reported after the transfer of the requested number of data ends when an error occurs at the time of reading. You.

Here, the SCSI controller 22
The well-known SCSI (Small Computer S)
The communication of the image data GD is performed according to a system interface. Various phases are prepared for SCSI, but in this example, the image data GD is transferred using the information transfer phase. The information transmission phase includes a command phase for transmitting a command, a data phase for performing data communication, and a status for transmitting a status used to confirm whether correct processing is being performed.
It consists of phases and so on.

Here, the SCSI controller 22 and the FIFO
Data transmission to and from O21 will be described with reference to FIG. FIG. 7A is a timing chart of the request signal req, FIG. 7B is a timing chart of the acknowledge signal ack, and FIG. 7C is a timing chart of the image data GD. The request signal req indicates that the transmission of the image data GD is ready (data is determined), and is low active. The acknowledge signal ack indicates that the image data GD has been received (latch has been completed), and is low active. In actual transmission, the I / O of the SCSI controller 22
After the image data GD is output to the O port, the SCSI controller 22 sets the request signal req to low level and notifies the FIFO 21 that the transmission is ready. When the FIFO 21 detects that the request signal req has become low level, it latches the image data GD and then makes the acknowledge signal ack low. Next, S
When the CSI controller 22 detects that the acknowledgment signal ack has gone low, it outputs the next image data GD to the I / O port.
Set req to low level. Hereinafter, this is repeated to transmit the image data GD. Thus, the image data GD
Is transmitted while confirming the result of the communication. When communication is performed normally, the delay time TD from the fall of the request signal req to the fall of the acknowledge signal ack is determined by the FIFO 21 and the SCSI controller 2.
It is determined by the specifications of 2.

A defect table 24 shown in FIG. 1 stores an address (sector number) of a defect area in association with a pointer. The pointer indicates the order of the defect areas on the hard disk 23, and the defect table 2
4 address. Here, an example of the contents of the defect table 24 is shown in FIG. In this example, sector 1 of the hard disk 23 is the first defect area, and the fifth defect area is sector K. In this way, by referring to the defect table 24, it is possible to know which sector on the hard disk 23 is the default area.

Reference numeral 25 denotes pointer setting means,
For the defect table 24, which address is to be read is specified. Specifically, when reading the image data GD from the hard disk 23, an initial value is input in accordance with an instruction from the CPU 10, and thereafter, as the reading of the image data GD proceeds, the next pointer is designated.

Reference numeral 26 denotes a first counter, which is constituted by a so-called ring counter, which generates a ripple carry when counting the number of data in one sector. A second counter 27 counts the ripple carry of the first counter 26. On the other hand, the second
As will be described later, when reading the image data GD, the address (start address SA) of the leading sector related to the reading is supplied as an initial value from the CPU 10 to the counter 27, so that the count value of the second counter 27 is Indicates the address (sector number) of the image data GD being read.

Reference numeral 28 denotes a comparator, which compares the address from the defect table 24 with the count value of the second counter.
If they do not match, a match control signal CS which is at low level is generated. Therefore, the match control signal CS is active (high level) while the default area is being read, and the match control signal CS is deactive (low level) while the normal storage area is being read.

Reference numeral 29 denotes a delay unit, which delays a signal for a predetermined time and outputs the signal. Note that the delay time is the same as in FIG.
Are set to match the TD shown in FIG. Reference numeral 30 denotes an inverter for inverting a signal, and reference numerals 31 to 34 denote buffers. The buffers 31 to 34 become active when their control inputs are at a low level, and enter a high impedance state when they are at a high level. Therefore, when the match control signal CS indicates a match (high level), the buffers 31 and 32 enter a high impedance state, and the buffers 33 and 34 enter an operating state.

Therefore, during the period in which the default area is being read, the request signal req from the SCSI controller 22 is transmitted to the delay unit 2 via the buffer 33.
9 is input. The delay unit 29 to which the request signal req is input delays the request signal req and outputs a pseudo acknowledge signal ack '. In this case, the delay time TD of the delay unit 29 is set so as to conform to the signal regulation of the SCSI controller 22.

2. Next, the operation of the present embodiment will be described with reference to the drawings. 2-1: Writing Operation of Image Data FIG. 5 is a flowchart for explaining the writing operation of the image data GD. In FIG. 5, the CPU 10 expands the image data GD on the main memory 13 and outputs the image data GD.
When the writing preparation of D is completed, the CPU 10 issues a write command and notifies the SCSI command to the SCSI controller 22 via the bus control unit 20 (step S1).

Next, a write command is executed by the SCSI controller 22 (step S2), and the CPU 10
Wait for the status of the CSI controller 22 to change (step S3). When the SCSI controller 22 issues a write command to the hard disk 23 and detects that the hard disk 23 is in a data standby state, it reports a status change to the CPU 10.

Thereafter, the CPU 10 determines whether or not a transition has been made to the data phase due to a change in status (step S4). If the process does not shift to the data phase, it means that there is some failure on the SCSI controller 22 side and data cannot be read or written. Therefore, the determination in step S4 is NO, and the process proceeds to step S13 to perform error processing.

On the other hand, when shifting to the data phase, the decision result in the step S4 is YES, the process proceeds to a step S5, and the CPU 10
Transfer the data count value to. SC that received this
The SI controller 22 sets the value in an internal counter. In this case, the data count value indicates the number of image data GD to be transferred. Thereby, SCS
The I controller 22 can detect whether a predetermined number of image data GD have been transferred.

Thereafter, the CPU 10 transfers the head address and the data count value of the image data GD stored in the main memory 13 to the bus control unit 20 (Step S).
6) The bus control unit 20 stores the head address and sets the data count value in the internal counter.

Next, transfer of the image data GD is executed (step S7). In this process, first, the bus control unit 20 accesses the main memory 13 with reference to the above-mentioned start address, and sequentially reads out the image data GD.
At this time, the internal counter of the bus control unit 20 counts down. As a result, the transfer number of the image data GD is measured, and when the internal counter becomes “0”, the image data G
The transfer of D is completed. When the bus control unit 20 transfers the image data GD to the SCSI controller 22 via the FIFO 21, the SCSI controller 22 writes the image data GD to the hard disk 23. SC
The SI controller 22 counts down the internal counter every time normal writing is performed, and measures the writing amount of the image data GD.

Next, the CPU 10 waits for a change in the status of the SCSI controller 22 (step S8). S
The CSI controller 22 determines whether or not the writing of the image data GD has been completed with reference to the count value of the internal counter (Step S9). If the count value of the internal counter is "0", it means that all the image data GD has been written, so the determination result is YES, and step S1 is performed.
0, the SCSI controller 22 returns “normal (go
od) is issued, the status is notified to the CPU 10 via the bus control unit 20, and the process is terminated.

On the other hand, in the SCSI controller 22, if the count value of the internal counter is not "0",
Since the writing of the image data GD has not been completed, the determination result of step S9 is NO, and the process proceeds to step S11 to determine whether a write error (Write Error) has occurred. Here, the write error means a recoverable error that cannot be written due to the influence of the defect area,
Irrecoverable errors such as seek section failure and head damage are excluded. If it is not a write error, it is considered an unrecoverable error.
The CSI controller 22 changes the status to abnormal (erro
Then, the process ends.

On the other hand, if it is a write error, step S1
The determination result of 1 is YES, and the process proceeds to step S12.
In this case, the SCSI controller 22 reports a write error to the CPU 10 via the bus control unit 20. This report includes the address (sector number) of the defect area in addition to the occurrence of the write error. The CPU 10 receiving the report stores the number of defect areas in the management table TB in the main memory 13 in association with the page number, and stores the address of the defect area in the defect table 24 via the bus control unit 20.

However, if the default area is detected again on the same page, a process of increasing the default number by "1" is performed. Therefore, the default number of the management table TB indicates the total number of default areas corresponding to the page. Thus, when reading the image data GD, the default number and the data size DS can be known for each page by referring to the management table TB. Further, since the data size DS per sector is predetermined, it is possible to obtain the number of data required when reading a certain range of image data GD from the hard disk 23.

When the registration of the defect area in the defect table 24 is completed, the process returns to step S1, and the remaining image data GD is written. This point will be specifically described with reference to FIG. For example, it is assumed that the sector of the hard disk 23 is configured as shown in FIG. 6A, and that 20 MByte of image data GD is written from sector 0. In this case, since sector n-3 is a default area, when sector n-3 is reached, S
The CSI controller 22 sends an error report to the CPU 10. Here, it is assumed that the address on the main memory 13 corresponding to the last image data GD written in the sector n-4 is ADR4, and the data amount of the image data GD to be written in the sector n-3 and thereafter is 5 MByte. In this case, since a writing error occurs in the sector n-3, the process returns from the step S12 to the step S1, and the remaining image data GD is stored. Here, step S6
The address transferred to the bus control unit 20 is ADR4 + 1. The data count value set in steps S5 and S6 is determined by calculating from the remaining amount of the image data GD. If there is no default area other than the sector n-3, for example, the image data GD is stored in a sector indicated by a vertical line in FIG.

2-2: Image Data Read Operation Next, FIG. 7 is a flowchart for explaining the image data read operation. First, the CPU 10 sends a read command to the SCSI controller 2 via the bus control unit 20.
2 (step S20), and instructs execution of the command (step S21). Thereafter, the CPU 10
It waits for a change in the status of the SCSI controller 22 (step S22).

On the other hand, the SCS receiving the read command
The I controller 22 responds to the instruction and
3 is issued. And SCS
When the hard disk 23 enters the data output state, the I-controller 22 reports this status change to the CPU 10. Based on this status, the CPU 10 determines whether or not it is the data phase (Step S23).

If the status indicates the data phase, the determination result is YES, and the process proceeds to step S24, where the CPU 10
The number of image data GD to be transferred is transferred as a data count value. The SCSI controller 22 that has received this sets the data count value in the internal counter (Step S24). The SCSI controller 22
During the reading period of the image data GD, down counting is performed using the internal counter, and when the count value becomes “0”, it is recognized that the reading of the image data GD is completed. If the hard disk 23 has a default area, the image data GD is not stored in the default area.
It is necessary to determine the data count value in consideration of the number of data corresponding to the default area in advance. Therefore, the CPU 1
0 is a management table T formed on the main memory 13
By accessing B, a data count value is determined in consideration of the number of defects DN corresponding to the image data GD to be read. For example, if the contents of the management table TB are as shown in FIG. 2, the storage capacity per sector is 1 MByte, and if the second page is to be read, the data count value is 3 * 3M + 12M = 21M.

Next, when the CPU 10 transfers the I / O address of the image data sending section 4 and the data count value to the bus control section 20, the bus control section 20 receiving the data transfers the I / O address and the data count value.
The / O address is stored, and the data count value is set in the internal counter (step S25). The data count value in this case is a data number that does not consider the defect number DN, unlike the case described above. this is,
Even if there is a default area in the readout range, the image data GD is continuously stored in the FIFO 21 as described later. Therefore, when measuring the number of image data GD transferred from the FIFO 21, the default This is because it is not necessary to consider the number.

Thereafter, the CPU 10 accesses the defect table 24 and checks whether or not a defect area exists in the read range (step S26). If a defect area exists, YES is determined, and step S2 is performed.
Proceeding to 7, the first pointer is set in the pointer setting means 25. For example, the content of the defect table 24 is shown in FIG.
If the read range is from sector J + 1 to sector L-1, the first pointer is "5".
Becomes

On the other hand, if no defect area exists in the range of the image data GD to be read, NULL is set in the pointer setting means 25. In this case, the output signal of the pointer setting means 25 is
4 is not instructed to output an address.

Next, the CPU 10 sets the start address SA of the image data GD to be read out on the hard disk 23 in the second counter 27 (step S2).
9). Prior to reading out the image data GD, the first
The count value of the counter 26 is reset by the CPU 10 to “0”. Further, the CPU 10 sets the data count value of the image data GD in the image data sending section 4 (Step S30).

Thereafter, data transfer is executed (step S31). Here, if there is no defect area in the read range, the image data GD is read from the hard disk 23, and the SCSI controller 22 → FIFO 21 →
The transfer is performed in the order of the bus control unit 20 → the image data transmission unit 4.

Next, the data transfer operation in the case where a defect area is present in the range to be read will be described with reference to the timing chart shown in FIG. In this example, the contents of the defect table 24 are as shown in FIG.
It is assumed that the image data GD from the data to the sector L-1 are read. Image data GD from the SCSI controller 22
When transfer starts, the request signal is synchronized
req is supplied to the first counter 26. Request signal r
Since eq changes from a high level to a low level every time the image data GD is ready to be transmitted, the number of image data GD output from the SCSI controller 22 is reduced by counting the number of falling edges.
Measured at 6. Since the start address SA is set in the second counter 27 (step S2).
9) The count value of the second counter 27 indicates the address (sector number) of the currently read image data GD. FIG. 7A illustrates the count value of the second counter 27.

In this example, the pointer setting means 25
Since the first pointer set by “1” is “5”, as shown in FIG.
The output data of 4 initially indicates the sector K. The output data of the defect table 24 and the count data of the second counter 27 are compared by a comparator 28. This allows
When they match, the match control signal CS goes high. In this example, first, during the period from time t1 to time t2, the coincidence control signal CS is at the high level as shown in FIG. 7C. During this period, buffer 3
1 and 32 are in a high impedance state, buffers 33 and 3
4 is in operation.

Therefore, during the period when the default area is being read, the request signal req from the SCSI controller 22 shown in FIG.
Is input to the delay unit 29 through the
The pseudo acknowledge signal ack 'shown in (d) is output. This pseudo acknowledge signal ack 'is
Is supplied to the SCSI controller 22 via the
The CSI controller 22 continues outputting the image data GD. This is because the delay time of the delay unit 29 is set so that the time difference TD between the pseudo acknowledge signal ack 'and the request signal req conforms to the signal regulation of the SCSI controller 22. On the other hand, buffers 31 and 32
Is in a high-impedance state.
The request signal req is not supplied to O21. Therefore, even if the image data GD is supplied to the FIFO 21 during the reading period of the default area, it is not input.

When the first counter 26 counts the request signal req for one sector, the count value of the 22nd counter is incremented to indicate "K + 1". Then, the point setting means 25 increments the pointer and supplies "6" to the defect table 24 (see FIG. 4). As a result, the output data of the defect table 24 changes to “K + 7”.
For this reason, as shown in FIG. 7C, the coincidence control signal CS indicates that the count value of the second counter 27 is K + from time t2.
7 until time t3 when the signal level is low and SC
Image data G from the SI controller 22 to the FIFO 21
D is transferred. As described above, during the period in which the defect area is being read, no data is transferred to the FIFO 21,
During the period when the normal storage area is being read, the FIFO 21
The data is transferred to Therefore, the image data GD is continuous inside the FIFO 21.

When the data transfer is executed, the process proceeds to step S32 shown in FIG.
Wait for a change in the status of the SI controller 22. Then, the SCSI controller 22 determines whether the transfer of the image data GD has been completed without any error (Step S).
33). If there is no error, it is determined as YES, the process proceeds to step S34, and a status indicating normality is reported to the CPU 10. On the other hand, if an error occurs, it is determined as NO, and the process proceeds to step S35. , A status indicating an error is reported to the CPU 10, and the process is terminated.

3. Conclusion As described above, according to the present embodiment, the image data GD
Is written to the hard disk 23, a defect area is detected and stored in the defect table 24, and when the image data GD is read, the defect table 2
4, the data read during the reading period of the area is set in the FIFO so as to be excluded from the image data GD.
21 and the SCSI controller 22 are controlled so that the image data GD can be output without lowering the processing speed.
Can read and write.

That is, the image data G is stored in the normal storage area.
D is written, and when the defect area is reached, writing of the image data GD is stopped and the rest of the image data GD is written in a sector adjacent to the defect area. There is no. As a result, the image data GD can be written at the highest writing speed realized by the hard disk 23.

The image data GD is transferred to the hard disk 2
When reading from the storage area 3, even if there is a defect area, the remaining image data GD can be immediately read from the storage area adjacent to the replacement area without moving the head to the replacement area. Reading is enabled. Further, since the image data GD is not stored in a large-capacity memory such as a page buffer, the processing can be completed in a short time.

4. Modifications The present invention is not limited to the embodiments described above,
Various modifications described below are possible. In the above-described embodiment, the image forming apparatus connected to the LAN has been described as an example. However, the image forming apparatus includes, in addition to a printer, an apparatus that forms an image by some means, such as a copying machine or a facsimile apparatus. Of course.

In the above-described embodiment, the data stored in the secondary storage device 2 has been described by taking the image data GD as an example. However, the present invention is not limited to this, and the type of the stored data may be different. Does not matter.

Further, in the above-described embodiment, the pseudo acknowledge signal ack 'is generated by using the delay unit 29. However, the signal specification of the SCSI controller 22 does not need to delay the acknowledge signal ack and the request signal req. If so, it goes without saying that the request signal req from the SCSI controller 22 may be used as it is in place of the pseudo acknowledge signal ack '.

In the above-described embodiment, the management table TB is generated at the time of writing the image data GD. However, when reading the image data GD, the CPU 10 accesses the defect table 24 and based on the contents thereof. , The management table TB may be generated at the time of reading. The contents of the defect table 24 are stored in the hard disk 2.
3 may be transferred to the defect table 24 when the image data GD is read.

Further, in the above-described embodiment, the secondary storage device 2 has been described as performing the writing and reading of the image data GD, but the present invention is not limited to this. Needless to say, a data storage device that can perform at least one of reading may be used. As a read-only data storage device, for example, a CD
-ROM is applicable. In this case, the defect area may be specified when the storage medium is inspected, the defect table 24 may be generated, and the defect table 24 may be stored in the recording medium.

In the above-described embodiment, the image data GD is not written in the hard disk 23 in the default area. However, during this period, dummy data may be generated and written in the hard disk 23. .

The points described above can of course be regarded as a data writing method and a data reading method, and a program for realizing such a method may be recorded on a recording medium. As the recording medium, for example, a magnetic recording medium such as a semiconductor memory, a floppy disk, and a magnetic tape, and an optical recording medium such as a CD-ROM can be used.

[0062]

As described above, according to the invention specifying matter according to the present invention, even if a defect occurs during use, data can be read and written with a simple configuration without lowering the processing speed. it can.

[Brief description of the drawings]

FIG. 1 is a block diagram of an image forming apparatus using a secondary storage device according to an embodiment of the present invention.

FIG. 2 is a SCSI controller 2 according to the embodiment;
6 is a timing chart for explaining data transmission between the FIFO 2 and the FIFO 21.

FIG. 3 is an explanatory diagram showing an example of the content of a management table TB according to the embodiment;

FIG. 4 is a defect table 24 according to the embodiment;
FIG. 4 is an explanatory diagram showing an example of the contents of the above.

FIG. 5 is a flowchart illustrating an operation of writing image data GD according to the embodiment;

FIG. 6 is an explanatory diagram for describing an example of an operation when a defect area occurs during writing in the embodiment.

FIG. 7 is a flowchart for explaining an image data reading operation according to the embodiment;

FIG. 8 is a timing chart for explaining data transfer according to the embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 CPU (write control means 22 SCSI controller (write means, read means) 23 Hard disk (storage means) 24 Defect table (defective area management means) 25 FIFO (data generation means) 28 Comparator (identification means, determination means) req request signal ack acknowledgment signal 29 delay unit (pseudo acknowledgment signal generating means) 31, 32 buffer (suspension means) 33, 34 buffer (pseudo acknowledgment signal generating means) 26 first counter (reading position specifying means) 27 second counter ( Reading position specifying means)

Continued on the front page (51) Int.Cl. ⁶ Identification code FI G11B 20/18 532 G11B 20/18 532B 572 572C 572F

Claims (7)

[Claims] 1. A storage unit for storing data, a writing unit for writing the data in the storage unit, a defective area management unit for storing a position of a defective area where normal writing is not possible, and a writing of the data During the writing period, when the defective area occurs, the writing unit is controlled to stop writing the data, and the position of the defective area is controlled to be stored in the defective area management unit. A data control device for controlling the writing means so as to restart writing of the data from an area adjacent to the defective area. 2. A storage device for storing data, a defective region management device for storing a position of a defective region where normal writing is impossible, a reading device for reading the data from the storage device, and the defective region management device. Data generating means for recognizing the position of the defective area with reference to the data, and generating output data by excluding data from the defective area in the data read by the reading means. Characteristic data storage device. 3. A reading means for reading the data from the storage means, and a position of the defective area is recognized with reference to the defective area management means, and among the data read by the reading means, the defective data is read. 2. The data storage device according to claim 1, further comprising a data generation unit configured to generate output data by excluding data from the area. 4. The reading means generates a request signal instructing a transmission request in synchronization with the read data, and after receiving an acknowledgment signal instructing reception confirmation from the data generating means, reads the next data. Output means, the data generation means for specifying a defective area read period for reading the data of the defective area with reference to the defective area management means, and data from the read means during the defective area read period. Interrupting means for interrupting fetching; during the defective area reading period, a pseudo acknowledgment signal generating means for generating a pseudo acknowledgment signal equivalent to the acknowledgment signal; and transmitting means for transmitting the pseudo acknowledgment signal to the reading means. The data storage device according to claim 2, further comprising: 5. A reading position specifying means for specifying a current reading position by measuring said request signal, and said specifying means is obtained by referring to said specified current reading position and said defective area managing means. 5. The data storage device according to claim 4, further comprising: a determination unit configured to compare a position of the defective area and determine a period in which the two coincide with each other as the defective read period. 6. The pseudo acknowledgment signal generating means,
6. The data storage device according to claim 4, wherein the pseudo acknowledgment signal is generated based on the request signal output from the reading unit. 7. The data storage device according to claim 1, wherein said defective area management means is formed inside said storage means.