JP2008181670A - Semiconductor memory device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semiconductor memory device capable of writing/reading data to/from a nonvolatile memory at a high speed. <P>SOLUTION: A control circuit 15 outputs, upon reception of a control signal indicating a write instruction, data written in an I/O buffer 11 to a write buffer 12, and simultaneously specifies a block in a flash memory which is a nonvolatile memory including data of a designated address as an update block, outputs all data in the update block to a work memory 13 via a high-speed bus 16, and writes the number of the update block in a block number register 18. The control circuit 15 specifies, upon reception of a control signal indicating a read instruction, a block including the data of a designated address, and outputs data as read data in the work memory 13 to the I/O buffer 11 if the number of the block matches the block number stored in the block number register 18. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a semiconductor memory device, and more particularly to a semiconductor memory device including a flash memory that can rewrite data in units of blocks.

  A flash memory is a ROM (Read Only Memory) that can electrically erase and rewrite data, and is currently widely used as a device for storing data in mobile phones, digital still cameras, and the like. In the rewriting of data in the flash memory, normally, a block including data to be rewritten in the flash memory is read to the external memory. The block is updated by writing data in another area of the external memory to the read block, and then the read block in the flash memory is erased, and the erased block is located at the position of the erased block. An updated block in external memory is written.

For example, Japanese Patent Application Laid-Open No. 2004-228867 attempts to increase the speed of data writing in contrast to such normal flash memory data writing. That is, Patent Document 1 includes a buffer memory in a memory card device including an EEPROM (Electrically Erasable Programmable Read Only Memory). When data is written, external data is sent to the buffer memory, and then the EEPROM block is read into the buffer memory. After the data in the block is rewritten in the buffer memory, the updated block is returned to the EEPROM.
Japanese Patent Laid-Open No. 5-46469

  However, in Patent Document 1 described above, after data from the outside is sent to the buffer memory, the data in the EEPROM is read out to the buffer memory, so that the speed of data writing is not yet sufficiently achieved.

  Conventionally, the speed of data reading from the flash memory has not been sufficiently achieved.

  Therefore, an object of the present invention is to provide a semiconductor memory device capable of writing data to a nonvolatile memory at high speed.

  Another object of the present invention is to provide a semiconductor memory device capable of reading data from a nonvolatile memory at high speed.

  In order to solve the above problems, a semiconductor memory device according to the present invention includes a plurality of blocks, a nonvolatile memory capable of rewriting data in units of blocks, and a memory for storing write data sent from the outside. A write buffer, a work memory for storing at least a block of the same size as the block of the non-volatile memory, the work memory and the non-volatile memory are connected, and a bit more than an external data bus In parallel with the take-in control, a take-in control for taking the write data into the write buffer when a wide internal data bus, a control signal indicating a write instruction from the outside, an address, and write data are input. All the data of the block in the nonvolatile memory specified by the address via the internal data bus Output to the work memory, erase all data of the block in the non-volatile memory, and output write data in the write buffer to a position corresponding to the address in the block in the work memory. And a control circuit for performing write control for outputting all data of the block in the work memory to the position of the block in the nonvolatile memory via the internal data bus.

  In addition, a semiconductor memory device according to the present invention includes a plurality of blocks, a nonvolatile memory capable of rewriting data in units of blocks, a write buffer for storing data sent from the outside, and at least the nonvolatile memory A work memory for storing a block having the same size as one block of the volatile memory, an internal data bus having a bit width wider than that of the external data bus, the work memory and the nonvolatile memory being connected A control circuit including a first storage unit that stores a block number of a block of the nonvolatile memory, and the control circuit receives a control signal indicating a write instruction, an address, and write data from the outside. The write data is taken into the write buffer and all data in the block in the non-volatile memory specified by the address is specified. To the work memory via the internal data bus, erase all data in the block in the nonvolatile memory, and write data in the write buffer to the address of the block in the work memory. And output all the data of the block in the work memory to the position of the block in the nonvolatile memory via the internal data bus, and the first storage unit The control circuit, when a control signal indicating a read instruction and an address are input from the outside, when the block number specified by the address and the block number in the first storage unit are the same, Outputting the data specified by the address in the block in the work memory to the outside; When not scratch, to output the data specified by the address in the nonvolatile memory to the outside.

  According to the semiconductor memory device of the present invention, the control circuit includes a fetch control for fetching the write data into the write buffer when a control signal indicating a write instruction, an address, and the write data are input from the outside. In parallel with this fetch control, all the data in the block in the nonvolatile memory specified by the address is output to the work memory via the internal data bus, and all the data in the block in the nonvolatile memory is erased. The write data in the write buffer is output to a position corresponding to the address in the block in the work memory, and then all the data in the block in the work memory is sent through the internal data bus to the non-volatile memory. Write control to output to block position, so write data to non-volatile memory It is possible to perform writing at a high speed.

  Further, according to the semiconductor memory device of the present invention, the control circuit receives a control signal indicating a write instruction, an address, and write data from the outside, and the block of the block in the non-volatile memory that is specified by the address. All data is output to the work memory via the internal data bus, the block number is stored in the first storage unit, and the control circuit receives the address when a control signal indicating a read instruction and an address are input from the outside. If the block number specified in step 1 is the same as the block number in the first storage unit, the data specified by the address in the block in the work memory is output to the outside. If not, the address in the nonvolatile memory is output. Because the data specified by is output to the outside, data can be read from the non-volatile memory at high speed It can be.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
<First Embodiment>
The present embodiment relates to a semiconductor memory device that outputs block data in a flash memory to a work memory in parallel with fetching of write data into a write buffer.

(Constitution)
FIG. 1 shows a configuration of a semiconductor memory device according to this embodiment. Referring to FIG. 1, a semiconductor memory device 100 includes a flash memory 10, an input / output buffer 11, a write buffer 12, a work memory 13, a decoder 14, a control circuit 15, a data bus 20, and an address. A bus 21, a control signal bus 22, and a high-speed bus 16 are included.

  The flash memory 10 is composed of a plurality of blocks. The size of one block is 32K words (one word is 32 bits), and one bank is constituted by m blocks.

  The data bus 20 is a bus through which write data and read data flow between the outside and the input / output buffer 11. The bus width of the data bus 20 is, for example, 32 bits wide.

The control signal bus 22 is a bus through which a control signal flows between the outside and the control circuit 15.
The high-speed bus 16 is a bus that connects the flash memory 10, the work memory 13, and the input / output buffer 11, and connects the write buffer 12 and the work memory 13. The bus width of the high-speed bus 16 is, for example, 128 to 256 bits wide.

  The input / output buffer 11 temporarily stores data input from the data bus 20 (write data) or data output to the data bus 20 (read data). The size of the write data and read data is, for example, 32 bits.

  The write buffer 12 stores data input from the data bus 20 and stored in the input / output buffer 11, that is, write data. The write buffer 12 has a capacity for storing one or a plurality of write data.

  The input / output buffer 11 and the write buffer 12 input / output data in a FIFO (First In First Out) format.

  The work memory 13 has a capacity for storing data of one block of the flash memory 10. The work memory 13 stores block data sent from the flash memory 10. The work memory 13 stores the data sent from the write buffer 12 at a position corresponding to the decoded address in the stored block.

The decoder 14 decodes an address input from the address bus 21.
The control circuit 15 includes a write operation flag storage unit 17 and a block number register 18.

  The write operation flag storage unit 17 stores a write operation flag that can be referred to from the outside. When the value of the write operation flag is “1”, it indicates that the write operation is being performed, and when the value of the write operation flag is “0”, it indicates that the write operation is not being performed.

  The block number register 18 stores the block number stored in the work memory 13.

  Here, it is assumed that the value stored in the register can be referred to and set from the outside, and the flag value can only be referenced from the outside. This also applies to the following embodiments.

  The control circuit 15 performs control based on control data input from the control signal bus 22.

  That is, the control circuit 15 performs the following control at the time of writing. The control circuit 15 receives the control signal indicating the write instruction and causes the data in the input / output buffer 11 to be output to the write buffer 12. In parallel with the output of the data to the write buffer, the control circuit 15 specifies a block (update block) in the flash memory 10 including the data of the address decoded by the decoder 14, and all the data of the block is stored. The data is taken out from the flash memory 10 to the work memory 13 via the high-speed bus 16, and then the number of the updated block is written into the block number register 18. Further, the control circuit 15 sets the write operation flag in the control circuit 15 to “1”, and then causes the data in the write buffer 12 to be output to a position corresponding to the decoded address in the work memory 13. All data in the update block in the flash memory 10 is erased. Then, the control circuit 15 causes all data in the work memory 13 to be output to the update block of the flash memory 10 via the high-speed bus 16. The control circuit 15 sets the write operation flag to “0” after the completion of data writing.

  The control circuit 15 performs the following control during reading. The control circuit 15 receives the control signal indicating the read instruction, specifies the block including the data of the address decoded by the decoder 14, the block number of the block, the block number stored in the block number register 18, and Compare If the comparison results match, the control circuit 15 causes the data in the work memory 13 to be output as read data to the input / output buffer 11 via the high-speed bus 16. If the comparison result does not match, the control circuit 15 causes the block data in the flash memory 10 specified by the decoded address to be output as read data to the input / output buffer 11 via the high-speed bus 16.

(Write operation)
Next, the write processing operation of the semiconductor memory device 100 will be described. FIG. 2 is a flowchart showing the operation procedure of the writing process.

  First, a control signal indicating a write instruction, write data, and an address are input from the outside to the control circuit 15, the input / output buffer 11, and the decoder 14 (step S301).

  In response to the control signal, the control circuit 15 causes the write buffer 12 to output write data in the input / output buffer 11. At the same time, the control circuit 15 identifies the block in the flash memory 10 including the data of the address decoded by the decoder 14 as an update block, and all the data in the update block is processed via the high-speed bus 16. Output to the memory 13. The control circuit 15 writes the updated block number in the block number register 18 (step S302).

  Next, the control circuit 15 sets the write operation flag to “1” (step S303), and then causes the write data in the write buffer 12 to be output to a position corresponding to the decoded address in the work memory 13. (Step S304).

  The control circuit 15 erases all data in the update block in the flash memory 10 (step S305).

  Next, the control circuit 15 causes all data stored in the work memory 13 to be output to the update block of the flash memory 10 (step S306).

Next, the control circuit 15 sets the write operation flag to “0” (step S307).
(Operation of read processing)
Next, the read processing operation of the semiconductor memory device 100 will be described. FIG. 3 is a flowchart showing the operation procedure of the reading process.

  First, a control signal indicating a read instruction and an address are input from the outside to the control circuit 15 and the decoder 14 (step S401).

  In response to the control signal, the control circuit 15 identifies the block containing the address data decoded by the decoder 14 and compares the block number of the block with the block number stored in the block number register 18. (Step S402).

  If the comparison results match, the control circuit 15 outputs the decoded address data stored in the work memory 13 as read data to the input / output buffer 11 via the high-speed bus 16 (step S403).

  If the comparison result does not match, the control circuit 15 outputs the decoded address data in the flash memory 10 to the input / output buffer 11 as read data via the high-speed bus 16 (step S404).

  The read data in the input / output buffer 11 is output to the outside via the data bus 20 (step S405).

  As described above, in the semiconductor memory device according to the present embodiment, when receiving the control signal indicating the write instruction, the control circuit 15 simultaneously outputs the write data in the input / output buffer 11 to the write buffer 12. Since the block in the flash memory 10 including the decoded address data is specified as an update block, and all the data in the update block is output to the work memory 13 via the high-speed bus 16, data is written at high speed. be able to.

  Further, the control circuit 15 writes the number of the updated block in the block number register 18, and the control circuit 15 receives the control signal indicating the read instruction, specifies the block including the data of the decoded address, and If the block number stored in the block number register 18 matches the block number stored in the block number register 18, the data in the work memory 13 is output as read data to the input / output buffer 11 via the high-speed bus 16. Can be read at high speed.

  Further, when the control circuit 15 receives the control signal instructing writing, the control circuit 15 sets the value of the write operation flag to “1” until all the data stored in the work memory 13 is output to the update block of the flash memory 10. Therefore, externally, referring to this write operation flag, when the value of the write operation flag is “1”, it is possible to prevent writing.

<Second Embodiment>
The present embodiment relates to a semiconductor memory device that outputs, to a work memory, only a block including valid data among blocks in a flash memory when data is written.

  FIG. 4 shows the configuration of the semiconductor memory device according to this embodiment. Of the constituent elements of the semiconductor memory device 50 shown in the figure, the same constituent elements as those of the semiconductor memory device 100 according to the first embodiment are denoted by the same reference numerals. Hereinafter, differences from the semiconductor memory device 100 according to the first embodiment will be described.

  The flash memory 56 includes a plurality of blocks and includes an validity flag storage unit 57. The validity flag storage unit 57 stores an validity flag for each block. When the value of the validity flag is “1”, this indicates that the data in the corresponding block is valid. When the value of the validity flag is “0”, all the data in the corresponding block is invalid. Indicates. Here, data is valid means that the data may be used in the future, and data is invalid if the data is not used in the future. This means that it is data and may be overwritten. When nothing is written in any block of the flash memory 56, the validity flags of all the blocks are set to “0”.

  When the control circuit 55 writes data to a block in the flash memory 56, the validity flag of the block is set to “1”.

  When the value of the validity flag of the update block in the flash memory 56 is “1”, the control circuit 55 writes the write data as in the first embodiment.

  On the other hand, when the value of the validity flag of the update block in the flash memory 56 is “0”, the control circuit 55 transfers all the data in the update block in the flash memory 56 to the work memory 13 via the high-speed bus 16. The process of outputting is not performed, and the process of erasing all the data in the update block in the flash memory 56 is not performed.

(Write operation)
Next, the write processing operation of the semiconductor memory device 50 will be described. FIG. 5 is a flowchart showing an operation procedure of the writing process.

  First, a control signal indicating a write instruction, write data, and an address are input from the outside to the control circuit 55, the input / output buffer 11, and the decoder 14 (step S501).

  In response to the control signal, the control circuit 55 causes the write buffer 12 to output the write data in the input / output buffer 11 (step S502).

  The control circuit 55 identifies the block including the data at the address decoded by the decoder 14 as an update block, and checks the validity flag of the update block (step S503).

  If the value of the validity flag is “1”, the control circuit 55 causes all data in the update block to be output from the flash memory 56 to the work memory 13 via the high-speed bus 16 (step S504).

  The control circuit 55 writes the update block number in the block number register 18 (step S505).

  Next, the control circuit 55 sets the write operation flag to “1” (step S506), and then causes the write data in the write buffer 12 to be output to a position corresponding to the decoded address in the work memory 13. (Step S507).

  The control circuit 55 erases all the data in the update block in the flash memory 56 (step S508).

  Next, the control circuit 55 causes all data stored in the work memory 13 to be output to the update block of the flash memory 56 (step S509).

Next, the control circuit 55 sets the write operation flag to “0” (step S510).
On the other hand, if the value of the validity flag is “0”, the control circuit 55 writes the update block number in the block number register 18 (step S511).

  Next, the control circuit 55 sets the write operation flag to “1” (step S512), and then causes the write data in the write buffer 12 to be output to a position corresponding to the decoded address in the work memory 13. (Step S513).

  Next, the control circuit 55 causes all data stored in the work memory 13 to be output to the update block of the flash memory 56 (step S514).

Next, the control circuit 55 sets the write operation flag to “0” (step S515).
Next, the control circuit 55 sets the validity flag corresponding to the update block to “1” (step S516).

(Operation of read processing)
Since the read processing operation of the semiconductor memory device 50 is the same as the read processing operation of the semiconductor memory device 100 according to the first embodiment, description thereof will not be repeated here.

  As described above, in the semiconductor memory device according to the present embodiment, when writing data, only blocks including valid data among the blocks in the flash memory are output to the work memory. Since a block consisting only of invalid data is not output to the work memory, the data writing speed can be increased.

<Third Embodiment>
The present embodiment relates to a semiconductor memory device including a write buffer that stores data of one or more blocks.

  FIG. 6 shows the configuration of the semiconductor memory device according to this embodiment. Of the constituent elements of the semiconductor memory device 200 shown in FIG. 9, the same constituent elements as those of the semiconductor memory device 100 according to the first embodiment are denoted by the same reference numerals. Hereinafter, differences from the semiconductor memory device 100 according to the first embodiment will be described.

  The semiconductor memory device 200 includes a plurality of write buffers 27a to 27c. Each write buffer has a capacity for storing data of one block. Write buffers 27a-c are ordered. The write buffer 27a is ordered first, the write buffer 27b is ordered second, and the write buffer 27c is ordered third.

The control circuit 25 includes the same block number register 18 as in the first embodiment.
The control circuit 25 outputs a plurality of write data input to the input / output buffer 11 to the write buffers 27a to 27c as follows.

  First, the control circuit 25 causes the write data input to the input buffer 11 to be output to the first write buffer 27a. The storage position of the first write data in the write buffer 27a is a position corresponding to the address. When the write data is stored up to the end position of the write buffer 27a, the control circuit 25 outputs the write data to the second write buffer 27b. Further, when the write data is stored up to the end of the write buffer 27b, the control circuit 25 outputs the write data to the third write buffer 27c.

  The control circuit 25 is a write buffer in which write data is stored among the write buffers 27a to 27c, and specifies the output write buffer sequentially from the write buffer in the order.

  The control circuit 25 specifies a block in the flash memory 10 determined by the address decoded by the decoder 14 and the order of the specified output write buffer as an update block. That is, when the output write buffer is the first write buffer 27a, the control circuit 25 specifies the block in the flash memory 10 including the data of the decoded address as an update block, and the output write buffer is the second write buffer. In the case of the buffer 27b, the first block subsequent to the block in the flash memory 10 including the data of the decoded address is specified as an update block. When the output write buffer is the third write buffer 27c, the decoded address is specified. The second block following the block in the flash memory 10 including the data is specified as an update block.

  The control circuit 25 causes all data in the update block to be output to the work memory 13 via the high-speed bus 16.

  The control circuit 25 causes all data in the output write buffer to be output to the work memory 13. Here, it is assumed that the write data from the outside is taken into the output write buffer by the time when the write data is output from the output write buffer to the work memory 13.

  The control circuit 25 erases all data in the update block in the flash memory 10. The control circuit 25 causes all data stored in the work memory 13 to be output to the update block of the flash memory 10.

(Write operation)
Next, the write processing operation of the semiconductor memory device 200 will be described. FIG. 7 is a flowchart showing the operation procedure of the writing process.

  First, a control signal indicating a write instruction, an address, and a plurality of write data are input from the outside to the control circuit 25, the decoder 14, and the input / output buffer 11 (step S601).

  The control circuit 25 causes the write data input to the input / output buffer 11 to be sequentially output from the write buffer with the first order to the write buffer (step S602).

  Next, the control circuit 25 identifies the write buffer in which the write data is stored and which has the earliest order as the output write buffer. Further, the control circuit 25 specifies a block in the flash memory 10 determined by the address decoded by the decoder 14 and the order of the specified output write buffer as an update block (step S603).

  The control circuit 25 causes all data in the update block to be output to the work memory 13 via the high-speed bus 16 (step S604).

  The control circuit 25 writes the update block number into the block number register 18 (step S605).

  The control circuit 25 outputs all the write data in the output write buffer to the work memory 13 (step S606).

  The control circuit 25 erases all data in the update block in the flash memory 10 (step S607).

  Next, the control circuit 25 causes all data stored in the work memory 13 to be output to the update block of the flash memory 10 (step S608).

  Next, the control circuit 25 continues the writing process when the write data is stored in any of the write buffers, and the write process when the write data is not stored in any of the write buffers. Is canceled (step S609).

(Operation of read processing)
Since the read processing operation of semiconductor memory device 200 is the same as the read processing operation of semiconductor memory device 100 according to the first embodiment, description thereof will not be repeated here.

  As described above, in the semiconductor memory device according to the present embodiment, the write buffer stores data of one or more blocks, and the control circuit sequentially transfers the data of each block in the write buffer to the corresponding block of the flash memory. Therefore, data can be written continuously from the outside.

<Fourth Embodiment>
The present embodiment relates to a semiconductor memory device that uses a work memory as a mirror memory. Here, the mirror memory means a memory that responds to external data writing and reading instead of the flash memory in response to external data writing and reading to the flash memory.

(Constitution)
FIG. 8 shows the configuration of the semiconductor memory device according to this embodiment. Of the constituent elements of the semiconductor memory device 30 shown in the figure, the same constituent elements as those of the semiconductor memory device 100 according to the first embodiment are denoted by the same reference numerals. Hereinafter, differences from the semiconductor memory device 100 according to the first embodiment will be described.

  The control circuit 35 includes a write control register 36, a work memory clear register 37, and a read completion flag storage unit 38.

  When the value of the write control register 36 is “1”, if the value of the work memory register 37 is “0”, the output of the data in the work memory 13 to the flash memory 10 is permitted.

  When the value of the write control register 36 is “0”, it indicates a state where the output of the data in the work memory 13 to the flash memory 10 is prohibited.

  When the value of the work memory clear register 37 is “1”, all data in the work memory 13 is initialized to “0”, and even if the value of the write control register 36 is “1”, the data in the work memory 13 This shows a state in which the output of the data to the flash memory 10 is prohibited.

  When the value of the work memory clear register 37 is “0”, if the value of the write control register 36 is “1”, it indicates that output of data in the work memory to the flash memory 10 is permitted.

  The read completion flag storage unit 38 stores a read completion flag. When the value of the read completion flag is “1”, the mirror memory setting is completed, that is, the reading of the block data of the flash memory 10 to the work memory is completed. When the value of the read completion flag is “0”, the mirror memory setting is not completed.

  When the control signal indicating the mirror memory setting instruction is input, the control circuit 35 identifies the block in the flash memory 10 including the data of the decoded address as a duplex block, and all of the duplex blocks are specified. Data is output to the work memory 13 via the high-speed bus 16. Then, the control circuit 35 sets the read completion flag to “1”. After the value of the read completion flag becomes “1”, a control signal indicating a write instruction or a control signal indicating a read instruction is input from the outside. The control circuit 35 writes the duplex block number into the block number register 18 and sets the value of the write control register 36 to “0”. When the value of the write control register 36 becomes “0”, data output from the work memory 13 to the flash memory 10 is prohibited.

  When a control signal indicating a write instruction is input, the control circuit 35 causes the write buffer 12 to output data in the input / output buffer 11. Then, the control circuit 35 compares the block number of the block including the data of the decoded address with the block number stored in the block number register 18, and only when the comparison result matches, the write buffer 12 The write data is output to a position corresponding to the decoded address in the work memory 13.

  When a control signal indicating a read instruction is input, the control circuit 35 performs the same processing as in the first embodiment. That is, the control circuit 35 specifies a block including data at the address decoded by the decoder 14 and compares the block number of the block with the block number stored in the block number register 18. If the comparison results match, the control circuit 35 causes the data in the work memory 13 to be output as read data to the input / output buffer 11 via the high-speed bus 16. If the comparison result does not match, the control circuit 35 causes the block data in the flash memory 10 specified by the decoded address to be output as read data to the input / output buffer 11 via the high-speed bus 16.

  When a control signal instructing clearing of the mirror memory is input, the control circuit 35 sets the value of the work memory clear register 37 to “1”. The control circuit 35 erases data in the work memory.

  When a control signal instructing backup is input, the control circuit 35 sets the value of the write control register 36 to “1”. When the value of the write control register 36 is set to “1” and the value of the work memory clear register 37 is set to “0”, the control circuit 35 stores the data of the duplicated block in the flash memory 10. And all the data in the work memory is output to the duplex block of the flash memory 10 via the high-speed bus 16.

(Mirror memory setting process operation)
Next, the operation of the mirror memory setting process of the semiconductor memory device 30 will be described. FIG. 9 is a flowchart showing the operation procedure of the mirror memory setting process.

  First, a control signal indicating a mirror memory setting instruction and an address are input from the outside to the control circuit 35 and the decoder 14 (step 701).

  Next, in response to the control signal, the control circuit 35 specifies a block in the flash memory 10 including the data of the address decoded by the decoder 14 as a duplex block, and all the data of the duplex block. Are output to the work memory 13 via the high-speed bus 16 (step S702).

The control circuit 35 sets the read completion flag to “1” (step S703).
The control circuit 35 writes the duplex block number in the block number register 18 (step S704).

  The control circuit 35 sets the value of the write control register 36 to “0” (step S705).

(Operation of read processing)
After the read completion flag is set to “1”, a control signal indicating a read instruction and an address are input from the outside to the control circuit 35 and the decoder 14, respectively. Since the following read operation is the same as that in the first to third embodiments, description thereof will not be repeated.

(Write operation)
Next, the write processing operation of the semiconductor memory device 30 will be described. FIG. 10 is a flowchart showing the operation procedure of the writing process.

  After the read completion flag is set to “1”, a control signal indicating a write instruction, write data, and an address are input from the outside to the control circuit 35, the input / output buffer 11, and the decoder 14 ( Step S801).

  In response to the control signal, the control circuit 35 outputs the data in the input / output buffer 11 to the write buffer 12 (step S802).

  In response to the control signal, the control circuit 35 compares the block number of the block including the address data decoded by the decoder 14 with the block number stored in the block number register 18 (step S803).

  The control circuit 35 outputs the write data in the write buffer 12 to a position corresponding to the decoded address in the work memory 13 only when the comparison results match (step S804).

(Operation of backup processing)
Next, the backup processing operation of the semiconductor memory device 30 will be described. FIG. 11 is a flowchart showing an operation procedure of backup processing.

  When a control signal instructing to clear the mirror memory is input from the outside to the control circuit 35 (step S901), the control circuit 35 sets the value of the work memory clear register 37 to “1” (step S902). .

The control circuit 35 erases the data in the work memory (step S903).
A control signal for instructing backup of the work memory to the flash memory is input to the control circuit 35 from the outside (step S904).

  The control circuit 35 receives the control signal and sets the value of the write control register 36 to “1” (step S905).

  The control circuit 35 checks the value of the write control register 36 and the value of the work memory clear register 37 (step S906).

  When the value of the write control register 36 is set to “1” and the value of the work memory clear register 37 is set to “0”, the control circuit 35 stores the data of the duplicated block in the flash memory 10. Is deleted (step S907).

  Then, the control circuit 35 outputs all the data in the work memory to the duplex block of the flash memory 10 via the high-speed bus 16 (step S908).

  As described above, according to the semiconductor memory device according to the present embodiment, when the control signal indicating the mirror memory setting instruction is input, the control circuit 35 transfers all data in the duplex block to the work memory 13. Output. The control circuit 35 writes the duplex block number into the block number register 18 and prohibits the output of data from the work memory 13 to the flash memory 10.

  When a control signal indicating a write instruction is input, the control circuit 35 compares the block number of the block including the data of the decoded address with the block number stored in the block number register 18, and the comparison result is Only when they match, the write data in the write buffer 12 is output to the work memory 13. Since data output from the work memory to the flash memory is not always performed, data can be written at high speed.

  When a control signal indicating a read instruction is input, the control circuit 35 performs the same processing as in the first embodiment, so that data can be read at high speed.

  In the semiconductor memory device according to the present embodiment, the control circuit 35 outputs all data in the work memory to the duplex block of the flash memory 10 when a control signal instructing backup is input. External data can be written to the flash memory.

<Fifth Embodiment>
The present embodiment relates to a semiconductor memory device that uses a work memory including a plurality of blocks corresponding to all blocks in a flash memory as a mirror memory.

(Constitution)
FIG. 12 shows the configuration of the semiconductor memory device according to this embodiment. Of the constituent elements of the semiconductor memory device 40 shown in FIG. 9, the same constituent elements as those of the semiconductor memory device 100 according to the first embodiment are denoted by the same reference numerals. Hereinafter, differences from the semiconductor memory device 100 according to the first embodiment will be described.

  As in the second embodiment, the flash memory 56 includes a plurality of blocks and includes an validity flag storage unit 57.

  The validity flag storage unit 57 stores an validity flag for each block. When the value of the validity flag is “1”, it indicates that the data in the corresponding block is valid. When the value of the validity flag is “0”, it indicates that the data in the corresponding block is invalid. Show. When nothing is written in any block of the flash memory 56, the validity flags of all the blocks are set to “0”.

  The work memory 47 includes the same number of blocks as the blocks in the flash memory 56, and each block has a corresponding block in the flash memory 56. The work memory 47 includes an validity flag storage unit 48 and an update flag storage unit 49.

  The validity flag storage unit 48 stores an validity flag for each block. When the value of the validity flag is “1”, it indicates that data is output from the corresponding block of the flash memory 56 to the corresponding block in the work memory 47. When the value of the validity flag is “0”, it indicates that data is not output from the corresponding block in the flash memory 56 to the corresponding block in the work memory 47.

  The update flag storage unit 49 stores an update flag for each block. When the value of the update flag is “1”, it indicates that the external write data is output to the corresponding block. When the value of the update flag is “0”, the external write data is output to the corresponding block. Indicates that it has not been.

  The control circuit 45 includes a read completion flag storage unit 38, a first write control register 43, a second write control register 41, a first work memory setting register 46, and a second work memory similar to those in the fourth embodiment. A setting register 42.

  When the value of the first write control register 43 is “1”, the output of the data in the work memory 47 to the flash memory 56 is permitted. When the value of the first write control register 43 is “0”, this indicates a state where the output of the data in the work memory 47 to the flash memory 56 is prohibited.

  The second write control register 41 stores a plurality of bits. When the value of the first bit is “1”, the output of the data in the work memory 47 to the flash memory 56 is permitted. When the value of the first bit is “1”, the value of the subsequent bit indicates the block number of the block instructed to perform backup. When the value of the first bit is “0”, it indicates a state where output of data in the work memory 47 to the flash memory 56 is prohibited.

  When the value of the first work memory setting register 46 is “1”, the mirror memory setting instruction is received. When the value of the first work memory setting register 46 is “0”, the mirror memory setting instruction is not received.

  The second work memory setting register 42 stores a plurality of bits. When the value of the first bit is “1”, it indicates that a mirror memory setting instruction has been received. When the value of the first bit is “1”, the value of the subsequent bit indicates the block number of the block instructed to perform mirror memory setting. When the value of the first bit is “0”, this indicates a state where no mirror memory setting instruction is received.

  Upon receiving the control signal indicating the mirror memory setting instruction, the control circuit 45 sets the value of the first work memory setting register 46 to “1”, and the validity flag of the blocks in the flash memory 56 is “1”. Identify the blocks. The control circuit 45 causes all data of the specified block in the flash memory 56 to be output to the work memory 47 via the high-speed bus 16. Thereafter, the control circuit 45 sets the validity flag of the block in the work memory 47 that has received data from the flash memory 56 to “1”, and sets the read completion flag to “1”. Thereafter, the control circuit 45 sets the value of the first write control register 43 and the value of the first bit of the second write control register 41 to “0”.

  When receiving a control signal indicating a read instruction, the control circuit 45 causes the input / output buffer 11 to output the address data decoded by the decoder 14 in the work memory 47 as read data.

  When receiving a control signal indicating a write instruction, the control circuit 45 outputs the write data in the input / output buffer 11 to a position corresponding to the address decoded by the decoder 14 in the work memory 47. Thereafter, the control circuit 45 sets the update flag of the block that has received the write data in the work memory 47 to “1”.

  When the control circuit 45 receives a control signal instructing partial resetting of the mirror memory, the control circuit 45 sets the value of the first bit of the second work memory setting register 42 to “1” and sets the value of the subsequent bit to the designated block. Make a number. When the value of the validity flag of the block in the flash memory 56 of the designated block number is “1”, the control circuit 45 works all the data of the block of the designated block number in the flash memory 56 via the high-speed bus 16. The corresponding block of the memory 47 is output, the validity flag of the block in the work memory 47 that has received data from the flash memory 56 is set to “1”, and the value of the read completion flag is set to “1”. Thereafter, the control circuit 45 sets the value of the first write control register 43 and the value of the first bit of the second write control register 41 to “0”.

  When the control circuit 45 receives a control signal instructing backup of the work memory 47 to the flash memory 56, the control circuit 45 sets the value of the first write control register 43 to “1”, and among the blocks in the work memory 47, the control circuit 45 is enabled. A block having a sex flag of “1” and an update flag of “1” is identified. The control circuit 45 erases all the data in the block in the flash memory 56 corresponding to the specified block in the work memory 47, and all the data in the specified block in the work memory 47 is corresponded in the flash memory 56. The validity flag of the corresponding block in the flash memory 56 that has received the data is set to “1”.

  In response to the control signal instructing partial backup, the control circuit 45 sets the value of the first bit of the second write control register 41 to “1” and sets the value of the subsequent bit to the designated block number. When the value of the validity flag of the block in the work memory 47 of the designated block number represented by the subsequent bit is “1” and the value of the update flag is “1”, the control circuit 45 stores the value in the work memory 47. All the data in the block in the flash memory 56 corresponding to the block with the designated block number is erased, and all the data in the block with the designated block number in the work memory 47 is output to the corresponding block in the flash memory 56. Thereafter, the control circuit 45 sets the validity flag of the block of the flash memory 56 to “1”.

(Mirror memory setting process operation)
Next, the operation of the mirror memory setting process of the semiconductor memory device 40 will be described. FIG. 13 is a flowchart showing the operation procedure of the mirror memory setting process.

  First, a control signal indicating a mirror memory setting instruction is input from the outside to the control circuit 45 (step S1001).

  In response to the control signal, the control circuit 45 sets the value of the first work memory setting register 46 to “1” (step S1002).

When the value of the first work memory setting register 46 is set to “1”, the control circuit 45 identifies a block with the validity flag “1” among the blocks in the flash memory 56 (step S1003). )
The control circuit 45 outputs all the data of the identified block in the flash memory 56 to the work memory 47 via the high-speed bus 16 (step S1004).

  The control circuit 45 sets the validity flag of the block in the work memory 47 that has received the data from the flash memory 56 to “1” (step S1005).

The control circuit 45 sets the read completion flag to “1” (step S1006).
The control circuit 45 sets the value of the first write control register 43 and the value of the first bit of the second write control register 41 to “0” (step S1007).

(Operation of read processing)
Next, the read processing operation of the semiconductor memory device 40 will be described. FIG. 14 is a flowchart showing the operation procedure of the reading process.

  After the read completion flag is set to “1”, a control signal indicating a read instruction and an address are externally input to the control circuit 45 and the decoder 14 (step S1101).

  In response to the control signal, the control circuit 45 outputs the address data decoded by the decoder 14 in the work memory 47 to the input / output buffer 11 as read data (step S1102).

  The read data in the input / output buffer 11 is output to the outside via the data bus 20 (step S1103).

(Write operation)
Next, the write processing operation of the semiconductor memory device 40 will be described. FIG. 15 is a flowchart showing an operation procedure of the writing process.

  After the read completion flag is set to “1”, a control signal indicating a write instruction, an address, and write data are externally input to the control circuit 45, the decoder 14, and the input / output buffer 11, respectively ( Step S1201).

  In response to the control signal, the control circuit 45 outputs the write data in the input / output buffer 11 to a position corresponding to the address decoded by the decoder 14 in the work memory 47 (step S1202).

  The control circuit 45 sets the update flag of the block that has received the write data in the work memory 47 to “1” (step S1203).

(Partial resetting operation of mirror memory)
Next, the operation of the mirror memory partial reset process of the semiconductor memory device 40 will be described. FIG. 16 is a flowchart showing the operation procedure of the mirror memory partial resetting process.

  First, a control signal instructing partial resetting of the mirror memory and a designated block number indicating a block to be reset are input from the outside to the control circuit 45 (step 1301).

  Upon receiving the control signal, the control circuit 45 sets the value of the first bit of the second work memory setting register 42 to “1” and sets the value of the subsequent bit to the designated block number (step S1302).

  When the first bit of the second work memory setting register 42 is “1”, the control circuit 45 checks the validity flag of the block in the flash memory 56 of the designated block number that is the value of the subsequent bit (step S1303). .

  When the value of the validity flag is “1”, the control circuit 45 outputs all data of the block of the designated block number in the flash memory 56 to the corresponding block of the work memory 47 via the high-speed bus 16 ( Step S1304).

  The control circuit 45 sets the validity flag of the block in the work memory 47 that has received data from the flash memory 56 to “1” (step S1305).

The control circuit 45 sets the value of the read completion flag to “1” (step S1306).
The control circuit 45 sets the value of the first write control register 43 and the value of the first bit of the second write control register 41 to “0” (step S1307).

(Operation of backup processing)
Next, the backup processing operation of the semiconductor memory device 40 will be described. FIG. 17 is a flowchart showing an operation procedure of backup processing.

  A control signal for instructing backup of the work memory 47 to the flash memory 56 is input to the control circuit 45 from the outside (step S1401).

  In response to the control signal, the control circuit 45 sets the value of the first write control register 43 to “1” (step S1402).

When the value of the first write control register 43 is set to “1”, the control circuit 45 has the validity flag “1” and the update flag “1” among the blocks in the work memory 47. Is identified (step S1403).
The control circuit 45 erases all data in the block in the flash memory 56 corresponding to the specified block in the work memory 47 (step S1404).

  The control circuit 45 causes all data of the specified block in the work memory 47 to be output to the corresponding block in the flash memory 56 (step S1405).

  The control circuit 45 sets the validity flag of the corresponding block in the flash memory 56 that has received the data in this way to “1” (step S1406).

(Partial backup processing operation)
Next, the operation of the partial backup process of the semiconductor memory device 40 will be described. FIG. 18 is a flowchart showing the operation procedure of the partial backup process.

  A control signal instructing partial backup of the mirror memory and a designated block number indicating a block to be backed up are input to the control circuit 45 from the outside (step S1501).

  Upon receiving the control signal, the control circuit 45 sets the value of the first bit of the second write control register 41 to “1” and sets the value of the subsequent bit to the designated block number (step S1502).

  When the value of the first bit of the second write control register 41 is “1”, the control circuit 45 checks the validity flag and update flag of the block in the work memory 47 of the designated block number represented by the subsequent bit ( Step S1503).

  When the validity flag is “1” and the update flag is “1”, the control circuit 45 erases all data in the block in the flash memory 56 corresponding to the block of the designated block number in the work memory 47. (Step S1504).

  The control circuit 45 outputs all the data of the block having the designated block number in the work memory 47 to the corresponding block in the flash memory 56 (step S1505).

  The control circuit 45 sets the validity flag of the block of the flash memory 56 to “1” (step S1506).

  As described above, in the semiconductor memory device according to the present embodiment, when the control circuit 45 receives the control signal indicating the setting instruction of the mirror memory, all the data of the predetermined block among the blocks in the flash memory 56 is received. Is output to the work memory 47, and data output from the work memory 47 to the flash memory 56 is prohibited.

  When receiving a control signal indicating a read instruction, the control circuit 45 outputs the decoded address data in the work memory 47 to the input / output buffer 11 as read data, so that the data can be read at high speed.

  When receiving the control signal indicating the write instruction, the control circuit 45 outputs the write data to a position corresponding to the decoded address in the work memory 47, so that the data can be written at high speed.

  In the semiconductor memory device according to the present embodiment, when receiving a control signal instructing backup of the work memory to the flash memory, the control circuit 45 includes the updated data in the blocks in the work memory 47. Since only the block causes the data in the block to be output to the corresponding block in the flash memory 56, waste of outputting the data of the block not including the updated data to the flash memory can be prevented.

(Modification)
The present invention is not limited to the above embodiment, and naturally includes the following modifications.

(1) Nonvolatile Memory Instead of the flash memory in the embodiment of the present invention, other electronically rewritable nonvolatile memories may be used.

(2) Write Operation Flag In the first embodiment, the control circuit 15 writes the update block number in the block number register 18 after receiving the control signal instructing the write, and then in step S303, the write operation flag is written. Although the operation flag is set to “1”, the present invention is not limited to this. The control circuit 15 may set the write operation flag to “1” at any time after receiving the control signal instructing writing until the update block number is written to the block number register 18.

(3) Flash memory block validity flag In the second and fifth embodiments, whether the flash memory block validity flag is a 2-bit value, data is written in the first bit. The second bit may be used to identify whether the data can be erased.

(4) Write Buffer In the third embodiment, the semiconductor memory device includes a plurality of write buffers 27a to 27c, and each write buffer stores one block of data. However, the present invention is limited to this. It is not a thing. For example, one write buffer may store one or a plurality of blocks of data.

(5) Timing for outputting write data from write buffer In the third embodiment, by the time when write data is output from each write buffer to the work memory, the external write data is taken into the write buffer. Assured.

  If it is not guaranteed that external write data is taken into the write buffer by the time when the write data is output from each write buffer to the work memory, the following control can be performed.

  That is, when the write control signal is asserted, it indicates a state in which write data is input from the outside, and when the write control signal is in a negate period, it indicates a state in which no write data is input from the outside. The control circuit can output write data from the write buffer to the work memory after the write control signal is negated when the write data is not stored up to the end of the write buffer.

  When the input of write data is started, the bit of the predetermined register in the control circuit is set to 1 from the outside, and when the input of the write data is finished, the bit of the predetermined register is set to 0 from the outside. Then, when the write data is not stored up to the end of a certain write buffer, the control circuit causes the write buffer to output the write data from the write buffer to the work memory after the bit of the predetermined register becomes 0. can do.

  Alternatively, when the number of input write data is a fixed value, the control circuit determines that the total number of write data fetched into all the write buffers is equal to this number when no write data is stored up to the end of a certain write buffer. After the fixed value is reached, write data can be output from the write buffer to the work memory.

(6) Work Memory In the third embodiment, the work memory has a capacity for storing data of one block of the flash memory 10, but is not limited to this. For example, the work memory may have a capacity corresponding to first to third blocks corresponding to the write buffers 27a to 27c.

  In this case, the write data in the write buffer 27a is output to the first block in the work memory, the write data in the write buffer 27b is output to the second block in the work memory, and the write buffer 27c The write data can be output to the third block of the work memory.

  In the third embodiment, the processing of S603 to S607 is continuously performed for one block, and then the processing of S603 to S607 is similarly performed for the next block. Can have three blocks, the processing of each step is continuously performed for three blocks, and then the processing of the next step is continuously performed for three blocks.

  In the third embodiment and this modification, the order of executing each process is different, but for each block, the process in S603, the process in S604, the process in S605, the process in S606, and the process in S607 are performed. Are the same in that

(7) Use of work memory In the fourth and fifth embodiments, the example in which the work memory is used as a mirror memory has been described. However, the present invention is not limited to this. The work memory may be used as a working memory or another memory.

  In the fifth embodiment, when the work memory is used as another memory, the memory has twice the capacity.

  Further, in the fifth embodiment, when the work memory is used as a working memory, an operation on the block can be performed without using an external memory by moving or copying the block in the work memory. Is possible.

(8) Capacity of work memory In the fourth embodiment, the work memory includes one block. However, the present invention is not limited to this, and the work memory includes an arbitrary number of blocks of 2 or more. It may be a thing.

(9) Work memory using 2-port RAM In the first to fifth embodiments, by using a 2-port RAM as a work memory, data input to the work memory and data output from the work memory can be performed simultaneously. Can be done.

(10) Input / output buffer In the first to fourth embodiments, write data from outside is once taken into the input / output buffer. However, the present invention is not limited to this, and write data from outside is directly written. It may be taken into a buffer.

(11) Simultaneous execution of fetching of data into the write buffer and output of data from the flash memory to the work memory In the second to fourth embodiments as well, as in the first embodiment, the control circuit When the control signal indicating the instruction is received, the write data in the input / output buffer 11 is output to the write buffer, and at the same time, the block of the flash memory including the data at the decoded address is specified as the update block, All data may be output to the work memory.

(12) Highway bus 16
In the embodiment of the present invention, the flash memory 10, the work memory 13, and the input / output buffer 11 are respectively connected by a high-speed bus 16 (128 to 256 bits wide). The high-speed bus 16 (128 to 256 bits wide) is connected between them. However, the present invention is not limited to this. The write buffer 12 and the work memory 13 may be connected by a bus that is slower than the bus that connects the flash memory 10 and the work memory 13. Similarly, the input / output buffer 11 and the work memory 13 and the flash memory 10 may be connected by a bus that is slower than the bus that connects the flash memory 10 and the work memory 13.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

1 is a diagram showing a configuration of a semiconductor memory device according to a first embodiment of the present invention. It is a flowchart which shows the operation | movement procedure of a write-in process. It is a flowchart which shows the operation | movement procedure of a read-out process. It is a figure which shows the structure of the semiconductor memory device concerning the 2nd Embodiment of this invention. It is a flowchart which shows the operation | movement procedure of a write-in process. It is a figure which shows the structure of the semiconductor memory device concerning the 3rd Embodiment of this invention. It is a flowchart which shows the operation | movement procedure of a write-in process. It is a figure which shows the semiconductor memory device concerning the 4th Embodiment of this invention. It is a flowchart which shows the operation | movement procedure of a mirror memory setting process. It is a flowchart which shows the operation | movement procedure of a write-in process. It is a flowchart which shows the operation | movement procedure of a backup process. It is a figure which shows the structure of the semiconductor memory device concerning the 5th Embodiment of this invention. It is a flowchart which shows the operation | movement procedure of a mirror memory setting process. It is a flowchart which shows the operation | movement procedure of a read-out process. It is a flowchart which shows the operation | movement procedure of a write-in process. It is a flowchart which shows the operation | movement procedure of a mirror memory partial reset process. It is a flowchart which shows the operation | movement procedure of a backup process. It is a flowchart which shows the operation | movement procedure of a partial backup process.

Explanation of symbols

  10, 56 Flash memory, 11 I / O buffer, 12 Write buffer, 13, 47 Work memory, 14 Decoder, 15, 55 Control circuit, 16 High-speed bus, 17 Write operation flag storage, 18 Block number register, 20 Data bus, 21 Address bus, 22 Control signal bus, 15, 25, 35, 45, 55 Control circuit, 26 Work memory update register, 36 Write control register, 37 Work memory clear register, 38 Read completion flag storage unit, 41 Second write control Register, 42 Second work memory setting register, 43 First write control register, 46 First work memory setting register, 57 Validity flag storage unit, 30, 40, 50, 100, 200 Semiconductor memory device.

Claims (2)

A non-volatile memory including a plurality of blocks and capable of rewriting data in units of blocks;
A work memory including a plurality of blocks corresponding to each block of the nonvolatile memory;
An internal data bus connecting the work memory and the non-volatile memory and having a bit width wider than an external data bus;
A control circuit,
When a control signal instructing use of the work memory as a mirror memory is input, the control circuit converts data in a predetermined block in the nonvolatile memory through the internal data bus. Output to the block
The control circuit, when a control signal instructing reading and an address are input, causes the data specified by the address in the block specified by the address in the work memory to be output to the outside,
When a control signal for instructing writing, an address, and write data are input, the control circuit places the write data in a position corresponding to the address in the block specified by the address in the work memory. Output
The control circuit erases data in a predetermined block in the non-volatile memory when a control signal instructing to back up the data in the work memory to the non-volatile memory is input. A semiconductor memory device that causes all data in a block in the work memory corresponding to the predetermined block to be output to the predetermined block in the nonvolatile memory. Corresponding to each block of the work memory, comprising a storage unit for storing an update flag indicating whether or not the data in the block is updated,
The control circuit updates an update flag corresponding to the block that has received the write data when the write data is output to the block in the work memory when a control signal instructing the write is input. Set to
The control circuit, when a control signal instructing to back up the data in the work memory to the nonvolatile memory is input, the block in which the update flag is set to be updated among the blocks of the work memory 2 only, the data in the block in the nonvolatile memory corresponding to the block is erased, and all the data in the block in the work memory is output to the block in the nonvolatile memory. Semiconductor memory device.

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