JP2003178280A - Memory card - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a memory card capable of reading and writing data at a high speed. <P>SOLUTION: When overwriting new data in a flash memory 1 with prerecorded data, a controller 5 pre-reads the data from the flash memory 1 with prerecorded data while recording the new data received from an external device on a buffer 2 or a buffer 3, and transfers the data to a refuge buffer 10. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a memory card having a flash memory, and more particularly to a memory card having an improved transfer speed between a host interface and flash memory.

[0002]

2. Description of the Related Art In recent years, memory cards have come to be used for storing large-capacity data with the increase in capacity of flash memories capable of holding data even when the power is off. Its applications are digital cameras, computers, as recording media replacing films, tapes, CDs, and MDs.
For example, a music reproducing device. Here, the audio reproducing device will be described with reference to FIG. 5. The audio reproducing device 52 decodes and reproduces the compressed audio data received from the memory card 54 via the host interface 53, and reproduces it from an external headphone or the like. It is heard by the speaker 51.

A flash memory used for a memory card has a limitation in use as well as an advantage that data can be retained even when the power is off. First, the erase unit is 32 pages (32 x 528 bytes) and the data erase time is 5 m.
Since s is required, it is impossible to write data during data erasing. Second, it takes 1 ms to write the transferred 528 bytes of data to the flash memory.
It takes time.

In order to overcome such restrictions peculiar to flash memories, conventional memory cards use a plurality of flash memories and a plurality of buffers. Here, a conventional memory card is shown in FIG. In FIG. 6, the memory card is a host interface 7
Interface 4 for receiving and outputting data, buffers 2 and 3 for temporarily recording data input from an external device, and a plurality of flash memories 1 for writing data. A flash memory group, a controller 5 that writes data to the flash memory 1 and reads data from the flash memory 1, and controls data writing, reading, or erasing operations of the flash memory 1 via the interface 4 and the controller 5. And a microcomputer 6 that operates.

The operation of the memory card configured as described above will be described. The data received from the external device is temporarily recorded in the buffer 2 or the buffer 3. The recorded data is transferred to the flash memory 1 and written therein. In this way, one write operation is completed.

When continuously writing data, the next data received from the external device is recorded in the buffer 3 while the data already recorded in the buffer 2 is being transferred to the flash memory 1. For example, when the buffer 2 and the buffer 3 can store 528 bytes of data, the time of transferring 512 bytes of data received via the host interface 7 to the buffer 2 or the buffer 3 with a 1-bit serial clock of 1 MHz is 0. .41
It is 0 ms. Therefore, when 2048 bytes are continuously transferred, the time to transfer the first 512 bytes of data to the buffer 2 is 0.410 ms, and the time to transfer the next 512 bytes of data to the buffer 3 is 0.410 ms. Then, after a write waiting time (1 ms) to the flash memory 1, data transfer to the buffers 2 and 3 is performed again, and the transfer of 2048 bytes is completed.

[0007]

However, in the conventional memory card, since the data transfer rate to the flash memory 1 is slower than the data transfer rate from the host interface 7, the overall data transfer rate is the flash memory 1 transfer rate. It was limited by speed. Therefore, since the data write time to the flash memory 1 is longer than the data transfer time, the performance of the memory card is determined by the write time to the flash memory and the size of the buffer.

When the flash memory 1 is erased while data is being written from the host interface 7, it is necessary to transfer the data from the flash memory 1 to the empty buffer 2 or the buffer 3 and save the data in the flash memory 1. Therefore, there is a drawback that continuous writing cannot be performed. Particularly, the data erasing time of the flash memory 1 is slower than the data transfer time, and 256M
It takes as long as 5 ms for a bit flash memory. Also,
Writing data to flash memory 1 takes 1ms
Requires. As described above, since the flash memory cannot overwrite the data, when rewriting the data in sector units, all the data in the block in which the original data exists is returned to the buffer 2 or the buffer 3 and other data that is not rewritten is written. You need to write to another block and write the data to be updated. After that, it was necessary to erase the block containing the original data.

Further, even if the overwrite data is one sector, it is necessary to read / write one block of data at the maximum to complete the writing to the flash memory, which is the reason why the transfer speed cannot be increased. . The present invention has been made to solve the above problems,
An object is to provide a memory card that can read and write data at high speed.

[0010]

In order to solve the above problems, a memory card according to claim 1 of the present invention temporarily stores data input from an external device and a flash memory group including a plurality of flash memories. A buffer to record in, and the operation of writing data to the flash memory,
In a memory card having a controller that executes a read operation of data from the flash memory or an erase operation of data recorded in the flash memory, the data read from the flash memory is temporarily recorded. When the new data received from the external device is recorded in the buffer, when the controller overwrites the flash memory in which the data is already recorded with the new data, the controller already stores the data in the buffer. The data is prefetched from the flash memory in which the data is recorded and transferred to the save buffer. As a result, while writing from the host interface to the host interface buffer, the flash memory is pre-read, the time required for overwriting is reduced, and high-speed data transfer is realized.

A memory card according to a second aspect of the present invention is the memory card according to the first aspect, wherein either the data received from the external device or the data read from the flash memory is selected. However, a selector for outputting to the save buffer is provided. Therefore, if the host interface specifies that the sector of a block unit or less is to be overwritten, you can select to write the necessary data of the block to be erased from the flash memory or to write the data of the host interface. The saved data can be directly written from the save buffer to a new block of the flash memory, and complicated processing related to overwrite can be simply performed.

A memory card according to a third aspect of the present invention includes a plurality of flash memory groups each including a plurality of flash memories, a buffer for temporarily recording data input from an external device, and the flash memory. A memory card having a controller for performing a data writing operation to the flash memory, a data reading operation from the flash memory, or an erasing operation of the data recorded in the flash memory. Record data temporarily,
When the controller has the same number of save buffers as the flash memory group and overwrites new data in the flash memory in which data is already recorded, the new data received from the external device is recorded in the buffer. While the data is being stored, the data is pre-read from the flash memory in which the data is already recorded and transferred to the save buffer. As a result, it is possible to pre-read a plurality of flash memories while writing to the buffer from the host interface, reduce the time required for overwriting, and realize high-speed data transfer.

A memory card according to a fourth aspect of the present invention is the memory card according to the third aspect, wherein either the data received from the external device or the data read from the flash memory is selected. However, the same number of selectors as the save buffers for outputting to the save buffers are provided. Therefore, if the host interface specifies that the sector of a block unit or less is to be overwritten, you can select to write the necessary data of the block to be erased from the flash memory or to write the data of the host interface. The saved data can be directly written from the save buffer to a new block of the flash memory, and complicated processing related to overwrite can be simply performed.

A memory card according to a fifth aspect of the present invention includes a flash memory group including a plurality of flash memories, an operation of writing data to the flash memory, an operation of reading data from the flash memory, or the above. In a memory card having a controller that performs an operation of erasing data recorded in the flash memory, a write buffer that temporarily records data received from an external device, and a data read from the flash memory. A read buffer for temporarily recording, and a save buffer for temporarily recording the data read from the flash memory,
When the controller overwrites new data in the flash memory in which the data is already recorded, the flash in which the data is already recorded is recorded while the new data received from the external device is recorded in the buffer. The data is prefetched from the memory and transferred to the save buffer. As a result, the size of the buffer can be minimized.

According to a sixth aspect of the present invention, in the memory card according to the fifth aspect, either the data received from the external device or the data read from the flash memory is selected. However, a selector for outputting to the save buffer is provided. Therefore, if the host interface specifies that the sector of a block unit or less is to be overwritten, you can select to write the necessary data of the block to be erased from the flash memory or to write the data of the host interface. The saved data can be directly written from the save buffer to a new block of the flash memory, and complicated processing related to overwrite can be simply performed.

According to a seventh aspect of the present invention, a memory card includes a plurality of flash memory groups each including a plurality of flash memories, a data write operation to the flash memory, and a data read from the flash memory. A controller that executes an operation or an operation of erasing the data recorded in the flash memory,
A memory card having a write buffer for temporarily recording data received from an external device, a read buffer for temporarily recording data read from the flash memory, and a read buffer for reading data from the flash memory. The flash memory group and the same number of evacuation buffers for temporarily recording the data, the controller receives the new data from the external device when the flash memory in which the data is already recorded is overwritten with new data. While the new data is recorded in the buffer, the data is pre-read from the flash memory in which the data is already recorded and transferred to the save buffer. As a result, the size of the buffer can be minimized.

A memory card according to claim 8 of the present invention is the memory card according to claim 7, wherein either the data received from the external device or the data read from the flash memory is selected. However, the same number of selectors as the save buffers for outputting to the save buffers are provided. Therefore, when the host interface specifies to overwrite the sector in block units or less, it is possible to select the writing of the necessary data of the block to be erased from the flash memory and the writing of the data of the host interface. It becomes possible to directly write the data to be written and the saved data from the save buffer to a new block of the flash memory, and it is possible to simply perform a complicated process related to overwriting.

The memory card according to claim 9 of the present invention is the memory card according to claim 5 or 7, wherein the write buffer and the read buffer are dual port memories. It is a feature. This allows data to be transferred to the flash memory while writing to the write-only buffer from the host interface,
Further, it is possible to realize a memory card which can be read to the host interface during writing to the read-only buffer from the flash memory and as a result can perform high-speed data transfer.

A memory card according to a tenth aspect of the present invention is the memory card according to any one of the first to ninth aspects, wherein the number of connected flash memories is (data from the host interface). It is characterized in that it is obtained from the formula of (transfer speed × writing time to flash memory) / (flash memory sector × 8 bits / data bus line of host interface). As a result, the data transfer of the host interface is not affected by the decrease in the transfer speed due to the writing time of the flash memory, so that a memory card capable of high-speed data transfer can be realized.

A memory card according to an eleventh aspect of the present invention is the memory card according to any one of the first to ninth aspects, in which the buffer capacity is
The number of flash memories x (data transfer rate from host interface x write time to flash memory) / (flash memory sector x 8 bits / data bus line of host interface) is there. This makes it possible to determine the size of the host interface buffer incorporated in the memory card in order to prevent the transfer of the host interface from being affected by the decrease in the transfer speed due to the writing time of the flash memory.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. The embodiment shown here is merely an example, and the present invention is not necessarily limited to this embodiment.

(Embodiment 1) Hereinafter, Embodiment 1 will be described.
The memory card according to FIG. 1 will be described with reference to FIG. FIG. 1 is a diagram showing a configuration of a memory card according to the first embodiment. In FIG. 1, a flash memory group is composed of a plurality of flash memories 1, and the flash memory 1 records data. Buffers 2 and 3
Then, the data input from the external device is temporarily recorded. Interface 4 is host interface 7
Receives data from an external device connected via. The controller 5 executes a data write operation to the flash memory 1, a data read operation from the flash memory 1, or an erase operation of the data recorded in the flash memory 1. The microcomputer 6
Writing data to the flash memory 1 via the interface 4 and the controller 5
Controls the read and erase operations of the data recorded in. When erasing a block of the flash memory 1, the save buffer 10 temporarily records data in the flash memory.

The number of connected flash memories is
The data transfer rate from the host interface × write time to the flash memory) / (flash memory sector × 8 bits / data bus line of the host interface) is used. For example, in a memory card that uses a flash memory with a write time of 300 μs and 512 bytes per sector, the host interface can transfer 10 Mbps with four data lines.
10 Mbps × 300 μsec / (512 × 8/4) = 2.
If it is composed of 92 ≈ 3 flash memories and provided with 3 host interface buffers (512 bytes), the data transfer from the host interface 7 can be performed due to the decrease in the transfer speed due to the write operation to the flash memory 1. Since it does not affect, it is possible to realize a memory card capable of high-speed data transfer.

If only one flash memory 1 is available due to the limitation of the substrate area of the memory card, the above method cannot solve the problem. Therefore, the capacity of the above-mentioned buffer is not calculated instead of determining the number of connected flash memories. The number of flash memories x (data transfer rate from host interface x write time to flash memory) / (flash memory sector x 8 bits / data bus line of host interface) is used for the calculation. For example, write time 300 μs, 512B per sector
This is a memory card that uses a single yte flash memory, and the host interface has 4 data lines and 10 Mb.
For ps transfer, 10 Mbps × 300 μsec / (51
2 × 8/4) = 2.92 = approx. 3 flash memories corresponding to a host interface buffer with a capacity of 512 bytes × 3, the write time of one flash memory is 300 μsec. Data can be held and written, and high-speed data transfer can be performed.

The operation of the memory card configured as described above will be described. First, a case where data received from an external device is written in the memory space of the flash memory 1 will be described. The data received from the external device is
It is temporarily recorded in the host interface buffer 2 or the host interface buffer 3. The recorded data is transferred from the host interface buffer 2 or the host interface buffer 3 to the write target flash memory 1, and the controller 5 performs a write operation to the write target flash memory 1 to save data in the memory card. Flash memory 1
The data is recorded in.

Next, a case where one sector data is overwritten by rewriting a part of the data already recorded in the flash memory 1 will be described. Before transferring the data received from the external device to the flash memory 1,
The controller 5 is informed that the next transfer data is overwrite data of one sector data. While the 1 sector data received from the external device is being written in the host interface buffer 2 or the host interface buffer 3, the controller 5 writes from the block including the overwrite sector to the overwrite sector from the flash memory 1 having the block to be overwritten. Valid data other than the above is read and transferred to the save buffer 10. After the data transfer to the save buffer 10 is completed, the controller 5
Is the block data other than one sector to be overwritten from the save buffer 10 and the host interface buffer 2.
Alternatively, the data of 1 sector recorded in the host interface buffer 3 is transferred to the flash memory 1 to which the overwrite data is recorded, and writing is performed. After the transfer of all data is completed, the overwritten original block is erased.

In the memory card according to the first embodiment, while the controller 5 for prefetching is recording one sector data in the buffer 2 or the buffer 3,
The save time for recording the overwrite block in the save buffer 10 can be shortened to speed up the write time to the flash memory.

(Second Embodiment) The second embodiment will be described below.
The memory card according to FIG. 2 will be described with reference to FIG. The difference from the first embodiment is that the same number of save buffers as the number of flash memory groups are provided.
FIG. 2 is a diagram showing the configuration of the memory card according to the second embodiment. In the figure, the same reference numerals are used for the same or the same components as in FIG. 1, and the description thereof is omitted. In the second embodiment, the controller 5 can control each flash memory group.

The operation of the memory card configured as above will be described. First, a case where data received from an external device is written in the memory space of the flash memory 1 will be described. The data received from the external device is
It is temporarily recorded in the host interface buffer 2 or the host interface buffer 3. The recorded data is transferred from the host interface buffer 2 or the host interface buffer 3 to the write target flash memory 1, and the controller 5 performs a write operation to the write target flash memory 1 to save data in the memory card. Flash memory 1
The data is recorded in.

Next, a case where one sector data is overwritten by rewriting a part of the data already recorded in the flash memory 1 will be described. Before transferring the data received from the external device to the flash memory 1,
The controller 5 is informed that the next transfer data is overwrite data of one sector data. While the 1 sector data received from the external device is being written in the host interface buffer 2 or the host interface buffer 3, the controller 5 writes from the block including the overwrite sector to the overwrite sector from the flash memory 1 having the block to be overwritten. Valid data other than the above is read and transferred to the save buffer 10. After the data transfer to the save buffer 10 is completed, the controller 5
Is the block data other than one sector to be overwritten from the save buffer 10 and the host interface buffer 2.
Alternatively, the data of 1 sector recorded in the host interface buffer 3 is transferred to the flash memory 1 to which the overwrite data is recorded, and writing is performed. After the transfer of all data is completed, the overwritten original block is erased.
The same number of save buffers 1 as the flash memory group
Since 0 is provided, the controller 5 can save the plurality of flash memories 1 at the same time, which improves the efficiency of the save operation. In addition, the buffer saving process is not limited to the writing process, but the data compression process and the data erasing process such as reducing the unused sectors in a block to combine continuous data into the same block in order to effectively use the flash memory 1 are performed in the flash memory group. At the same time, the internal data can be organized faster as a memory card.

In the memory card according to the second embodiment as described above, the same number of save buffers 1 as flash memory groups are provided.
Since 0 is provided, the saving processing of a plurality of flash memories can be performed at the same time, the efficiency of the saving operation is improved, and the speed of data transfer can be increased as a whole.

(Third Embodiment) The third embodiment will be described below.
The memory card according to FIG. 3 will be described with reference to FIG. FIG. 3 is a diagram showing the configuration of the memory card according to the third embodiment. In the figure, the same or corresponding components as those in FIG. 1 are designated by the same reference numerals, and the description thereof will be omitted. In FIG. 3, the write buffer 11 temporarily records the data received from the external device. The read buffer 12 temporarily records the data read from the flash memory 1.

The operation of the memory card configured as above will be described. First, a case where data received from an external device is written in the memory space of the flash memory 1 will be described. The data received from the external device is
It is temporarily recorded in the write buffer 11. The recorded data is transferred from the write buffer 11 to the write target flash memory 1 and written into the write target flash memory 1 by the controller 5. In this way, the data is recorded in the flash memory of the memory card.

Next, a case where data existing in the memory space of the flash memory 1 is read will be described. Data is read from the flash memory 1 by the controller 5 and transferred to the read buffer 12,
It is recorded temporarily. Then, the read buffer 12
The data recorded in 1 is output to the host interface 7 of the external device via the interface 4. In this way, the external device connected to the memory card can read the data in the memory card.

The write buffer 11 and the read buffer 12 described above have a large difference in write and read times depending on the characteristics of the flash memory 1. Therefore, by setting the write buffer 11 and the read buffer 12 to have optimum capacities, the time required for writing data to or reading data from the external device to the memory card is made comfortable.

At this time, in order to read the data from the flash memory 1, the control code for controlling the reading of the data from the flash memory 1 and the address of the flash memory 1 to be read are input, and then the read target is read. It takes time until the data is read from the flash memory 1. To write data to the flash memory 1, a control code for controlling the writing of data to the flash memory 1 and the address of the flash memory 1 to be written are input, and the write data 1 is written.
It takes time to transfer the sectors to the flash memory 1 to be written, input the actual write control code to the flash memory 1, and complete the writing. As described above, in the normal flash memory, the write time is about 10 times as long as the access time at the time of reading. Therefore, when writing and reading are performed at the same speed, the memory capacity required for the buffer has a difference of 10 times. Therefore, in order to realize high-speed data transfer, the capacities of the write buffer 11 and the read buffer 12 are set to a ratio of access time and write time at the time of reading.

In the memory card according to the third embodiment, the read buffer 12 for temporarily recording the buffer read from the flash memory 1,
A write buffer 11 for temporarily recording data received from an external device, and writing data to the write buffer 11 by using the write buffer 11 and the read buffer 12 as a dual port memory. The data can be transferred to the flash memory 1 while the data is being read, and the data can be read from the host interface 7 while the data is being transferred from the flash memory 1 to the read buffer 12. As a result, data transfer can be speeded up.

(Embodiment 4) A memory card according to Embodiment 4 will be described with reference to FIG. FIG. 4 is a diagram showing the configuration of the memory card according to the fourth embodiment. In the figure, the same reference numerals are used for the same or corresponding components as in FIG.
In FIG. 4, the first selector 21 selects the data read from the flash memory 1 or the data received from the external device. The second selector 22 is
The data read from the flash memory 1 or the data received from the external device is selected. The first save buffer 23 records the data selected by the first selector 21. The second evacuation buffer 24 is the second
The data selected by the selector 22 is recorded.

The operation of the memory card configured as above will be described. A case where data received from an external device is written in the memory space of the flash memory 1 will be described. The data received from the external device is transferred to the write buffer 11. Write buffer 1
The data recorded in 1 is transferred to the flash memory 1 to be written, and is written in the flash memory 1 to be written by the controller 5. In this way, data is recorded in the flash memory 1 of the memory card.

Next, a case where data existing in the memory space of the flash memory 1 is read will be described. The controller 5 that controls the flash memory 1 and the host interface 7 transfers data from the flash memory 1 to the read buffer 12. By transmitting the data recorded in the read buffer 12 to the host interface 7 of the external device via the interface 4, the external device can read the data of the memory card.

Next, a description will be given of a case of overwriting data which rewrites a part of the data already recorded in the flash memory 1. Before the data is received from the external device, the fact that the data to be transferred next is overwrite data is transmitted to the controller 5 that controls writing and reading to the flash memory 1. The controller 5
Before the external device writes data from the host interface 7 to the first save buffer 23 or the second save buffer 24, valid data that is not overwritten from the block including the overwrite data from the flash memory 1 of the overwrite target block Is transferred to the first save buffer 23 or the second save buffer 24. After the transfer to the first save buffer 23 or the second save buffer 24 is completed, the controller 5 transfers the data to be overwritten to the first save buffer 23 or the second save buffer 24. . The data to be overwritten is transferred from the first save buffer 23 or the second save buffer 24 to the flash memory 1 for newly storing, and is written to the flash memory 1. After the transfer of all data is completed, the overwritten original block is erased.

In the memory card according to the fourth embodiment, data transfer to the first save buffer 23 and the second save buffer 24 is performed by the host interface 7.
The data received from the flash memory 1 and the data read from the flash memory 1 can be selected, the operation of the flash memory save processing is performed by the host interface 7, the data from the flash memory 1 is saved by the first save buffer 23,
Alternatively, since the data to be newly written in the block is stored in the second save buffer 24 and the write operation to the flash memory 1 is performed in a batch process, the time for overwriting the flash memory is shortened and the memory is easy to use. Cards can be provided.

[0043]

As described above, according to the memory card of the first aspect of the present invention, a flash memory group including a plurality of flash memories and a buffer for temporarily recording data input from an external device. And a controller for performing a data write operation to the flash memory, a data read operation from the flash memory, or an erase operation of the data recorded in the flash memory, the flash memory comprising: The controller has a save buffer for temporarily recording the data read from the, and when the controller overwrites the new data in the flash memory in which the data is already recorded, the new data received from the external device is While the data is being recorded in the buffer, the above data is already written. Since the data is pre-read from the flash memory that is being written and transferred to the save buffer, the flash memory pre-read is performed while writing to the host interface buffer from the host interface, and the time required for overwriting To achieve high-speed data transfer.

According to the memory card of claim 2 of the present invention, in the memory card of claim 1, whichever of the data received from the external device and the data read from the flash memory is used. Since the selector for selecting whether or not to output to the save buffer is provided, when the host interface specifies overwriting of sectors in block units or less, it is necessary to write the necessary data in the block to be erased from the flash memory. It is possible to select writing of data of the host interface, and it becomes possible to directly write the data to be overwritten and the saved data from the saving buffer to a new block of the flash memory, so that complicated processing related to the overwriting can be simply performed.

According to another aspect of the memory card of the present invention, a plurality of flash memory groups each including a plurality of flash memories, a buffer for temporarily recording data input from an external device, In a memory card having a controller that performs a data write operation to the flash memory, a data read operation from the flash memory, or an erase operation of the data recorded in the flash memory, a read operation from the flash memory is performed. Equipped with the same number of evacuation buffers as the flash memory group for temporarily recording the output data, and the controller, when overwriting the flash memory in which the data is already recorded with new data, from the external device The new data received is recorded in the buffer. While the data is being written, the data is pre-read from the flash memory in which the data is already recorded and transferred to the save buffer. Pre-reading can be performed, the time required for overwrite is reduced, and high-speed data transfer is realized.

According to the memory card of claim 4 of the present invention, in the memory card of claim 3, either the data received from the external device or the data read from the flash memory. Select from or output to the evacuation buffer, and the same number of selectors as the evacuation buffer are provided, so if the host interface specifies to overwrite sectors in block units or less, it is erased from the flash memory. You can select to write the required data of the block or the data of the host interface, and the overwriting data and the saved data can be written directly from the save buffer to a new block of the flash memory, which is a complicated process for overwriting. Can be done simply.

According to the memory card of claim 5 of the present invention, a flash memory group including a plurality of flash memories, a data write operation to the flash memory, and a data read operation from the flash memory. Or a controller for executing an erasing operation of the data recorded in the flash memory, and a write buffer for temporarily recording the data received from the external device, and a memory card read from the flash memory. The controller includes a read buffer for temporarily recording the read data and a save buffer for temporarily recording the data read from the flash memory. When overwriting data,
While the new data received from the external device is recorded in the buffer, the data is prefetched from the flash memory in which the data is already recorded and transferred to the save buffer. The size of can be minimized.

According to a sixth aspect of the present invention, in the memory card according to the fifth aspect, either the data received from the external device or the data read from the flash memory is used. Since the selector for selecting whether or not to output to the save buffer is provided, when the host interface specifies overwriting of sectors in block units or less, it is necessary to write the necessary data in the block to be erased from the flash memory. It is possible to select writing of data of the host interface, and it becomes possible to directly write the data to be overwritten and the saved data from the saving buffer to a new block of the flash memory, so that complicated processing related to the overwriting can be simply performed.

According to the memory card of claim 7 of the present invention, each comprises a plurality of flash memories.
A memory card having a plurality of flash memory groups and a controller for executing a data write operation to the flash memory, a data read operation from the flash memory, or an erase operation of data recorded in the flash memory , A write buffer for temporarily recording the data received from the external device, a read buffer for temporarily recording the data read from the flash memory, and a temporary buffer for the data read from the flash memory. Recording buffer, the same number of save buffers as the flash memory group, and when the controller overwrites new data on the flash memory in which the data is already recorded, the new data received from the external device Is recorded in the above buffer During that, the already pre-read the data from the flash memory in which data is recorded. Thus transferred to the save buffer, can be reduced to the minimum necessary size of the buffer.

According to the memory card of claim 8 of the present invention, in the memory card of claim 7, either the data received from the external device or the data read from the flash memory. The number of selectors is the same as that of the save buffer for selecting and outputting to the save buffer. Therefore, if the host interface specifies overwriting of sectors in block units or less, the block to be erased from the flash memory. Required data writing and host interface data writing can be selected, and as a result, overwriting data and saved data can be written directly from the save buffer to a new block of flash memory, which complicates overwriting. Simple processing That.

According to the memory card of claim 9 of the present invention, in the memory card of claim 5 or 7, the write buffer and the read buffer are each a dual port memory. Therefore, data can be transferred to the flash memory while writing to the write-only buffer from the host interface, and can be read to the host interface while writing to the read-only buffer from the flash memory. As a result, a memory card capable of high-speed data transfer can be realized.

According to a tenth aspect of the present invention, there is provided a memory card according to any one of the first to ninth aspects.
In the memory card described in the item, the number of connected flash memories is (data transfer rate from host interface x write time to flash memory) /
(Flash memory sector x 8 bits / data bus line of host interface) Since it is calculated from the formula, the data transfer of the host interface is not affected by the decrease in transfer speed due to the write time of the flash memory, so high-speed data transfer is possible. It is possible to realize a memory card capable of performing.

According to the eleventh aspect of the present invention, there is provided the memory card according to any one of the first to ninth aspects.
In the memory card described in the paragraph, the capacity of the buffer is (flash memory number) x (data transfer rate from host interface x write time to flash memory) / (flash memory sector x 8 bits / host interface data Since it is calculated from the formula of (bus line), the size of the host interface buffer built in the memory card can be determined in order not to affect the transfer of the host interface by the decrease in transfer speed due to the write time of the flash memory. it can.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a memory card according to a first embodiment.

FIG. 2 is a diagram showing a configuration of a memory card according to a second embodiment.

FIG. 3 is a diagram showing a configuration of a memory card according to a third embodiment.

FIG. 4 is a diagram showing a configuration of a memory card according to a fourth embodiment.

FIG. 5 is a diagram showing an example of an audio reproducing device.

FIG. 6 is a diagram showing a configuration of a conventional memory card.

[Explanation of symbols]

1 Flash memory A few buffers 4 interfaces 5 controller 6 microcomputer 7 Host interface 10 Evacuation buffer 11 Write buffer 12 Read buffer 21 first selector 22 second selector 23 First Evacuation Buffer 24 Second evacuation buffer

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G11C 16/02 G11C 17/00 601A

Claims (11)

[Claims] 1. A flash memory group including a plurality of flash memories, a buffer for temporarily recording data input from an external device, a data write operation to the flash memory, and a data read from the flash memory. A memory card having a controller for performing an operation or an operation of erasing the data recorded in the flash memory, and comprising a save buffer for temporarily recording the data read from the flash memory, When the controller overwrites new data on the flash memory in which the data is already recorded, the flash memory in which the data is already recorded is recorded while the new data received from the external device is recorded in the buffer. Read ahead the data from and save the above Transferred to the buffer, a memory card, characterized in that. 2. The memory card according to claim 1, further comprising a selector that selects either the data received from the external device or the data read from the flash memory and outputs the selected data to the save buffer. A memory card characterized by the following. 3. A plurality of flash memory groups each comprising a plurality of flash memories, a buffer for temporarily recording data input from an external device, a data write operation to the flash memory, In a memory card having a controller that performs a data read operation or a data erase operation on the flash memory, the flash memory that temporarily records the data read from the flash memory. When the controller has the same number of save buffers as the group and overwrites new data in the flash memory in which the data is already recorded, while the new data received from the external device is recorded in the buffer. , The above data already recorded Memory card read ahead the data from Yumemori, transfers to the save buffer, characterized in that. 4. The save card according to claim 3, wherein either the data received from the external device or the data read from the flash memory is selected and output to the save buffer. A memory card having as many selectors as there are buffers for use. 5. A flash memory group composed of a plurality of flash memories, an operation of writing data to the flash memory, an operation of reading data from the flash memory, or an operation of erasing data recorded in the flash memory. In a memory card having a controller for executing, a write buffer for temporarily recording data received from an external device, and a read buffer for temporarily recording data read from the flash memory,
And a save buffer for temporarily recording the data read from the flash memory, wherein the controller receives the data from the external device when the flash memory in which the data is already recorded is overwritten with new data. A memory card, wherein while the new data is recorded in the buffer, the data is pre-read from the flash memory in which the data is already recorded and transferred to the save buffer. 6. The memory card according to claim 5, further comprising a selector that selects either the data received from the external device or the data read from the flash memory and outputs the selected data to the save buffer. A memory card characterized by the following. 7. Each of a plurality of flash memories,
A memory card having a plurality of flash memory groups and a controller for executing a data write operation to the flash memory, a data read operation from the flash memory, or an erase operation of data recorded in the flash memory In, a write buffer for temporarily recording the data received from the external device, a read buffer for temporarily recording the data read from the flash memory,
The controller has the same number of save buffers as the flash memory group for temporarily recording the data read from the flash memory, and the controller overwrites the flash memory in which the data is already recorded with new data. In this case, while the new data received from the external device is recorded in the buffer, the data is prefetched from the flash memory in which the data is already recorded and transferred to the save buffer. And a memory card. 8. The save card according to claim 7, wherein either the data received from the external device or the data read from the flash memory is selected and output to the save buffer. A memory card having as many selectors as there are buffers for use. 9. The memory card according to claim 5, wherein the write buffer and the read buffer are:
A memory card characterized by comprising dual port memories. 10. The method according to any one of claims 1 to 9.
In the memory card described in the paragraph, the number of connected flash memories is calculated by the following formula: (data transfer rate from host interface x write time to flash memory) / (flash memory sector x 8 bits / host interface data bus line) A memory card that is characterized by a greater demand. 11. The method according to any one of claims 1 to 9.
In the memory card described in the paragraph, the capacity of the buffer is (flash memory number) x (data transfer rate from host interface x write time to flash memory) / (flash memory sector x 8 bits / host interface data A memory card characterized in that it is obtained from the formula of (bus line).