JP2003323597A - Memory card - Google Patents

Abstract

(57) [Summary] To provide a memory card capable of reducing the circuit scale. A source code described in Java (TM) is converted (compiled) into bytecode and downloaded from a digital device to a memory card. The bytecode (class file) downloaded to the memory card 1 is static in the virtual machine 130.
Variable part, Applet code and static
It is separated into the final variable part. The part where rewriting may occur (the part of static variable) is E
A part stored in the EPROM 150 and having no possibility of rewriting (Applet code and static
The final variable part) is stored in the flash memory 200 after being encrypted by the encryption processing unit 170.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a memory card, and more particularly to a memory card that downloads program data and stores it in a nonvolatile memory.

[0002]

2. Description of the Related Art Memory cards are used for writing / reading information in digital devices such as digital cameras, PDAs, portable audios, mobile phones, and personal computers. The memory card has two chips, a flash memory and a controller. In recent years, the flash memory mounted on a memory card has been increasing in capacity, and accordingly, large-scale data can be stored in the flash memory. However, at present, memory cards only exchange data with digital devices. Some IC cards can download and execute application programs. However, the capacity of the non-volatile memory for storing the program is much smaller than the capacity of the flash memory mounted on the memory card.

An object of the present invention is to provide a memory card whose circuit scale can be reduced.

[0004]

A memory card according to the present invention comprises a first non-volatile memory, a second non-volatile memory, and a separating section. The first nonvolatile memory has a predetermined erase unit. The second nonvolatile memory has an erase unit larger than the erase unit of the first nonvolatile memory. The separating unit separates at least a portion of the program data downloaded to the memory card where rewriting may occur, stores the separated portion in the first nonvolatile memory, and stores the remaining portion in the second nonvolatile memory. Stored in the memory.

In the above memory card, in the execution process of the downloaded program, the rewriting process of the data in the program does not occur in the second non-volatile memory but occurs only in the first non-volatile memory. In this way, by performing the rewriting process of variables and the like in the first non-volatile memory having a small erase unit, the required buffer size is smaller than that in the case of performing the process in the second non-volatile memory having a large erase unit. The circuit scale can be reduced.

The size of the data temporarily buffered for rewriting is smaller in the first non-volatile memory than in the second non-volatile memory. Therefore,
The buffering processing time for rewriting can be reduced as compared with the case where the rewriting processing is performed in the second nonvolatile memory, and the processing time required for rewriting can be shortened.

Further, since the downloaded program data is stored separately in the first non-volatile memory and the second non-volatile memory, the security is improved.

Preferably, the program data is composed of a function and a variable. The separation unit stores the function in the second non-volatile memory, stores one of the variables that may be rewritten in the first non-volatile memory, and rewrites the variable. What is not possible is stored in the second non-volatile memory.

Preferably, the program data is a class written in an object-oriented programming language. The separation unit stores the variable of the class in the first non-volatile memory and stores the method of the class in the second non-volatile memory.

Preferably, the program data is a class written in an object-oriented programming language. The separation unit stores, in the first non-volatile memory, variables of the class that may be rewritten, and variables of the class that are not likely to be rewritten and the variables of the class. The method is stored in the second non-volatile memory.

Preferably, the memory card further includes an encryption processing unit. The encryption processing unit encrypts the remaining portion to be stored in the second non-volatile memory. Then, the first non-volatile memory, the separation unit, and the encryption processing unit are formed on the same chip.

In the above memory card, the program data stored in the second non-volatile memory is encrypted by the encryption processing section, so that the security is further improved.

Preferably, the first non-volatile memory is an EEPROM and the second non-volatile memory is a flash memory.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will now be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are designated by the same reference numerals, and the description thereof will not be repeated.

<Overall Configuration of Memory Card System> FIG.
FIG. 1 is a block diagram showing an overall configuration of a memory card system according to an embodiment of the present invention. In the system shown in FIG. 1, a digital device 2 (for example, a digital camera
(PDA, portable audio, mobile phone, personal computer, etc.)
Insert the memory card 1 into the slot (not shown)
Program data is downloaded from the digital device 2 to the memory card 1. The downloaded program is executed inside the memory card 1.

<Digital Device 2> The digital device 2 is a Java (T) which is an object-oriented programming language.
The source code described in M) is converted (compiled) into a byte code and transferred to the memory card 1.

<Memory Card 1> The memory card 1 includes a controller chip 100 and a flash memory chip 20.
With 0 and.

The controller chip 100 includes interfaces 110, 140 and 180, a CPU 120, a virtual machine 130, an EEPROM 150, and a buffer R.
It includes AMs 145 and 160 and a cryptographic processing unit 170.

The interface 110 is an interface between the digital device 2 and the controller chip 100. The interface 110 is the digital device 2
Class file downloaded from (byte code)
To the virtual machine 130.

The virtual machine 130 has an interface 1
The static variable is separated from the class file given by 10 and supplied to the interface 140, and the rest (applet code and static final
Variable) is supplied to the buffer RAM 160. Further, the virtual machine 130 converts the program data (byte code) read from the EEPROM 150 and the flash memory chip 200 into a format executable by the CPU 120 by an interpreter method.

The CPU 120 executes the program converted by the virtual machine 130. Also, the CPU 120
Controls the operation of the controller chip 100.

The interface 140 is the virtual machine 1.
30 and the CPU 120 and the EEPROM 150 and the buffer RAM 145.
The interface 140 uses the virtual machine 130
The tent variable is EEP via the buffer RAM 145.
Transfer to the ROM 150.

The buffer RAM 145 is the EEPROM 1
The data to be transferred to 50 and the data output from the EEPROM 150 are buffered. Also buffer R
The AM 145 temporarily buffers the data recorded in the EEPROM 150 when rewriting the data.

The EEPROM 150 stores static variables from the interface 140. EEPRO
M150 is a non-volatile memory that erases data in word units.

The buffer RAM 160 is used for the virtual machine 13
Applet code from 0 and static fi
The nal variable is temporarily stored. Also buffer RAM1
Reference numeral 60 temporarily stores the program data read from the flash memory 200 and decrypted by the cryptographic processing unit 170.

The cryptographic processing section 170 has a buffer RAM 16
The program data (applet code and static final variable) stored in 0 is encrypted and supplied to the interface 180. Also, the encryption processing unit 17
0 decodes the program data read from the flash memory chip 200.

The interface 180 is an interface between the controller chip 100 and the flash memory chip 200. The interface 180 is
Program data encrypted by the cryptographic processing unit 170 (applet code and static fina
(l variable) is transferred to the flash memory chip 200.
The interface 180 also transfers the program data read from the flash memory chip 200 to the encryption processing unit 170.

The flash memory chip 200 uses the encrypted program data (ap
(plet code and static final variables)
Memorize The flash memory chip 200 is a non-volatile memory that erases data in block units or chip units. That is, the flash memory chip 200
The erase unit is larger than that of the EEPROM 150.

<Download of Program> Next, referring to FIG.
Digital device 2 in the memory card system shown in
The download of the program data from the memory card 1 to the memory card 1 will be described.

Here, the program data of the source code as shown in FIG. 2 is downloaded. The source code shown in FIG. 2 is an application program for using the memory card 1 as a point card,
It is written in Java (TM). In this program, points are added at different point return rates for each item purchased (food, clothing, electrical appliances). The point balance is recorded for each purchased item. The point balance is declared as a static variable because it is updated each time a product is purchased. On the other hand, since the point return rate remains unchanged at the initial setting value, it is declared as a static final variable.

A source code written in Java (TM) is converted (compiled) into a byte code and downloaded from the digital device 2 to the memory card 1. In the virtual machine 130, the bytecode (class file) downloaded to the memory card 1 is a static variable portion, an Applet code, and a staticfi.
It is separated into the nal variable part. The part of the Applet code and staticfinal variable is stored in the flash memory 200, and the part of the static variable is E.
It is stored in the EPROM 150. As described above, the portion in which rewriting may occur (static variable portion) is stored in the EEPROM 150, and the portion in which rewriting does not occur (Applet code and st
The portion of the atic final variable) is the cryptographic processing unit 170.
It is stored in the flash memory 200 after being encrypted by. In an IC card that can download and execute an application program, as shown in FIG. 2, all downloaded bytecodes (class files) are stored in the internal EEPROM without being separated.

Next, the separation process performed in the virtual memory 130 will be specifically described with reference to FIG.

The class file downloaded from the digital device 2 to the memory card 1 includes an applet code part (method), a static final variable, and a static variable. applet
The first 1 byte of the code part is 0x01. stati
The first byte of the c final variable is 0x02.
The first 1 byte of the static variable is 0x03. As described above, in the class file compiled in the digital device 2, the applet code portion, the static final variable, and the static variable can be identified by determining the first byte. This determination is performed by the address analysis unit 131 of the virtual machine 130.

The storage unit 132 stores the flash memory 200 or the EEPR according to the determination result of the address analysis unit 131.
The program data is stored in the OM 150. When it is determined that the first byte is 0x01, the program data (applet code part) is stored in the flash memory 200. When it is determined that the first 1 byte is 0x02, the program data (static
The final variable) is stored in the flash memory 200 (after being encrypted by the encryption processing unit 170). When it is determined that the first 1 byte is 0x03, the program data (static variable) is stored in the EEPROM 150.

As a result of the above processing, as shown in FIG. 4, the flash memory 200 stores the applet code and the static final variable, and the EEP
The ROM 150 stores static variables.

<Execution of Downloaded Program> Next, the flash memory 200 and the EEPROM 150.
The execution processing of the program stored separately in the following will be described. The processing executed here is the processing of the content shown in the source code of FIG. Hereinafter, FIG. 5 (b)
A description will be given with reference to (c).

When the purchase amount (value) and the index (i) indicating the item type are input to the CPU 120,
The virtual machine 130 is an app on the flash memory 200.
The "instruction" stored in the let code part (addPoint) is fetched, and in the interpreter part,
It is converted into an executable format by the CPU 120 by an interpreter method. The converted instruction is executed by the CPU 120. In this way, the following processing is performed.

<Step ST51> _load ... ka on the flash memory 200
i-th data of ngenritu array (kangen
Ritu [i]) is acquired (X).

<Step ST52> _mul ... Value and kangenritu
Multiply with [i].

<Step ST53> _load ... point on the EEPROM 150
The i-th data (point [i]) of the t array is acquired (Y).

<Step ST54> _add ... Adds the result of the multiplication process in step ST52 and the point [i] obtained in step ST53.

<Step ST55> _bastore ... The result of the addition process in step ST54 is point [i] on the EEPROM 150.
(Z). That is, the content of point [i] is rewritten.

<Effect> In the present technology, EEPR
The storage capacity of OM is much smaller than that of flash memory. Therefore, in the case of a large-scale program, it becomes necessary to store it in the flash memory.

Normally, when executing a program, a process of rewriting small data (variables, etc.) in the program occurs. When the program stored in the flash memory is executed, this rewriting process is performed in erase units. However, the erase unit of the flash memory is EE
It is much larger than the erase unit of PROM. Therefore, when executing a program stored in the flash memory, a huge buffer memory is required for rewriting variables.

For example, in the case of a NAND flash memory having a storage capacity of 512 Mbit, a program unit of 512 bytes = 1 page, and an erase unit of 32 pages, 16 kby.
te buffer RAM is required.

In the memory card system according to the embodiment of the present invention, a portion (stati) in which program data (class file) downloaded from the digital device 2 to the memory card 1 may be rewritten (stati).
c variable) is stored in the EEPROM 150, and there is no possibility that rewriting will occur (Applet code and s
(tatic final variable) to the flash memory 20
It is stored in 0. Therefore, the rewriting process of the data in the program does not occur in the flash memory 200 but only in the EEPROM 150. As described above, since the variable rewriting process is performed in the EEPROM 150 having a small erase unit, the capacity of the buffer memory (buffer RAM 145) required for the rewriting process is smaller than that in the flash memory 200 having a large erase unit. The circuit scale can be reduced. Further, the size of the data temporarily buffered for rewriting is smaller in the EEPROM 150 than in the flash memory 200. Therefore, the buffering processing time for rewriting can be shortened as compared with the case where rewriting processing is performed in the flash memory 200, and the processing time required for rewriting can be shortened.

In addition, the program data downloaded to the memory card 1 is transferred to the flash memory 200 and the EEPR.
Since it is stored separately from the OM 150, security is improved. Since the program data stored in the flash memory chip 200 is encrypted by the encryption processing unit 170, security is further improved.

Further, when accessing the program data stored in the EEPROM 150, it is not necessary to perform the encryption / decryption processing, so that the processing time is improved.

Here, the static variable is set to EEP.
Stored in ROM150, Applet code and st
The static final variable is stored in the flash memory 200, but the static variable and static f
The internal variable is stored in the EEPROM 150, and Appl
The et code may be stored in the flash memory 200.

If the time required for reading from the flash memory 200 and the decryption processing by the encryption processing unit 170 is longer than the time required for reading from the EEPROM 150, the CPU 120 controls the flash memory 200 to be accessed frequently. EEPRO
You may write in M150.

In addition, the buffer RAM 145 and the buffer R
This RAM is composed of one common RAM with AM160.
When the EEPROM 150 is operating, the EEPROM 15
It may be operated as the 0 buffer RAM, and may be operated as the flash memory 200 buffer RAM when the flash memory 200 is operating. As a result, the circuit area required for the RAM can be reduced,
The circuit scale can be reduced.

[Brief description of drawings]

FIG. 1 is a block diagram showing an overall configuration of a memory card system according to an embodiment of the present invention.

FIG. 2 is a diagram showing how program data downloaded from a digital device is stored in a memory card.

FIG. 3 is a diagram showing how program data downloaded from a digital device is stored in a memory card.

FIG. 4 is a diagram showing program data stored in a flash memory and an EEPROM.

5A to 5C are diagrams for explaining a program execution procedure.

[Explanation of symbols]

1 memory card, 100 controller chips, 20
0 flash memory chip (second non-volatile memory), 130 virtual machine (separation unit), 150 EEP
ROM (first non-volatile memory), 170 cryptographic processing unit.

Continued front page    (72) Inventor Ryoichi Sugita             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. (72) Inventor Miki Mizushima             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. (72) Inventor Takafumi Kikuchi             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. F-term (reference) 5B017 AA07 BA07 CA14                 5B035 AA00 AA13 BB09 CA11                 5B076 AB08 BA04 BA07 BA10

Claims (6)

[Claims] 1. A memory card, comprising: a first nonvolatile memory having a predetermined erasing unit; and a second nonvolatile memory having an erasing unit larger than the erasing unit of the first nonvolatile memory. At least a portion where rewriting may occur in the program data downloaded to the memory card is separated, the separated portion is stored in the first nonvolatile memory, and the remaining portion is stored in the second nonvolatile memory. A memory card comprising: a separation unit for storing in a memory. 2. The program data according to claim 1, wherein the program data includes a function and a variable, and the separation unit stores the function in the second non-volatile memory, and rewriting of the variable occurs. A memory card, wherein a possible one is stored in the first non-volatile memory, and one of the variables that is not likely to be rewritten is stored in the second non-volatile memory. 3. The program data according to claim 1, wherein the program data is a class described in an object-oriented programming language, and the separation unit stores a variable of the class in the first non-volatile memory. A memory card, wherein the method is stored in the second non-volatile memory. 4. The program data according to claim 1, wherein the program data is a class written in an object-oriented programming language, and the separating unit selects one of the variables of the class that may be rewritten. 1. A memory card, characterized in that it is stored in a first non-volatile memory, and variables of the class that are unlikely to be rewritten and methods of the class are stored in the second non-volatile memory. 5. The encryption processing unit according to claim 1, further comprising an encryption processing unit that encrypts the remaining portion to be stored in the second nonvolatile memory, the first nonvolatile memory, the separating unit, and the A memory card characterized in that the encryption processing unit is formed on the same chip. 6. The memory card according to claim 1, wherein the first non-volatile memory is an EEPROM, and the second non-volatile memory is a flash memory.