WO2006126777A1

WO2006126777A1 - Sharing memory interface

Info

Publication number: WO2006126777A1
Application number: PCT/KR2006/000808
Authority: WO
Inventors: Jong-Sik Jeong
Original assignee: Mtekvision Co., Ltd.
Priority date: 2005-05-23
Filing date: 2006-03-08
Publication date: 2006-11-30
Also published as: US7827337B2; US20080183942A1; KR100589227B1

Abstract

A device and a method for sharing a memory interface are disclosed. According to preferred embodiments of the present invention, a supplementary control unit included in a digital processor can control some of the pins, constituting a memory interface, to be shared by a plurality of memory. With the present invention, the number of pins included in a memory interface can be minimized, thereby reducing the size of a supplementary control unit, saving the manufacturing cost, and improving the processing efficiency.

Description

[DESCRIPTION]

[Invention Title]

SHARING MEMORY INTERFACE

[Technical Field]

The present invention is related to sharing a memory interface, more

specifically to a device having a memory interface sharing function and a method

thereof.

[Background Art]

Generally, an electric/electronic device refers to a device designed to perform a

predetermined function (or functions) through a combination of electric/electronic parts.

The mobile communication terminal, which is one of the most popular

electric/electronic devices, is essentially a device designed to enable a mobile user to

telecommunicate with a receiver who is remotely located. Thanks to scientific

development, however, the latest mobile communication terminals have functions, such

as camera and multimedia data playback, in addition to the basic functions, such as

voice communication, short message service, and address book.

As such, the device performing multiple functions (i.e. the main function and additional functions) comprises a plurality of processors. In other words, one or more

application processors, which control and perform additional functions, and a main

processor, which controls the overall operation of the device and the operation of the

application processor, can be comprised. For example, for a mobile communication

terminal that processes an image signal, the main processor controls the communication

function as well as the overall operation of the mobile communication terminal, and the

application processor controls the processing of the image signal, under the control of

the main processor.

Other than the mobile communication terminal described above, there can be a

variety of portable terminals, such as personal digital assistants (PDA) and portable

multimedia players (PMP), which comprise a plurality of processors to perform

multiple functions. Here, portable terminals refer to electronic devices that can be easily

carried by making the size compact in order to perform functions such as game and

mobile communication.

Having an electric/electronic device perform multiple functions requires one or

more storage devices for storing data and information required for the functions.

Common storage devices include NAND flash memories and SD (Secure Digital) cards.

The NAND flash memory is directly coupled to the phone board of a mobile

communication terminal, and thus it is not possible to be removed by the user. On the

other hand, the SD card can be removed by the user since the socket is mounted on the phone board.

An internal system of a device having a plurality of processors and a plurality

of memories is illustrated in Fig. 1 and Fig. 2.

Fig. 1 is a diagram showing a device, in which a plurality of memories are used,

and Fig. 2 is a block diagram outlining an application processor in accordance with the

prior art.

As shown in Fig. 1, in the device for performing multiple functions, a main

processor 110 and an application processor 120 are coupled through a bus, which is for

communicating data and/or information, and the application processor 120 is coupled to

one or more memories. A bus refers to a common-purpose electrical route, used for the

communication of information between processors or between a processor and a

memory.

The application processor 120 can be coupled to an SD card 130 and a NAND

flash memory 140, and interfaces for coupling the memories 130 and 140. In other

words, the application processor 120 operates the plurality of memory interfaces as

necessary to store multimedia data in any of the memories or to read and playback the

stored data.

Referring to Fig. 2, the application processor 120 comprises a processing unit

210, a bus controller 220, a first memory controller 230, and a second memory

controller. The processing unit 210 performs predetermined functions (e.g. MPEG4, 3-D

graphics, and camera), designed to be performed by the application processor 120. The

processing unit 210 also controls the bus controller 220 by interpreting instructions

(including information on which interface to use) received from the main processor 110

and delivering the instruction to the bus controller. The processing unit 210 can be, for

example, a 32-bit processor.

The bus controller 220 performs internal bus control such that the first memory

controller 230 or the second memory controller 240 is operated by the control of the

processing unit 210.

The first memory controller 230 performs data and/or information

communication with the SD card 130 through the first memory interface. Usually, a

9-pin interface is used for the first memory interface, which is in the application

processor, for coupling to the SD card 130. The 9-pin interface is structured with 4 data

signal pins (i.e. SD DATO, SD DATl, SD DAT2, and SD DAT3) and 5 control signal

pins (i.e. CLK signal, Command signal, Card Detect signal, Power Control signal, and

Write Protect signal).

The second memory controller 240 performs data and/or information

communication with the NAND flash memory 140 through the second memory

interface. Usually, a 14-pin interface is used for the second memory interface, which is

in the application processor, for coupling to the NAND flash memory 140. The 14-pin interface is structured with 8 data signal pins (i.e. NF DataO, NF Datal, NF Data2, NF

Data3, NF Data4, NF Data5, NF Dataβ, and NF Data7) and 6 control signal pins (i.e.

CS (Chip Select) signal, CLE (Command Latch Enable) signal, ALE (Address Latch

Enable) signal, REN (Read Enable) signal, WEN (Write Enable) signal, and WP (Write

Protection) signal).

Since the conventional device has to have all memory interfaces that can be

coupled, a total of 23 pins (9 pins for the SD card 130 and 14 pins for the NAND flash

memory 140) are needed in the case illustrated by Figs. 1 and 2.

In most devices, however, the application processor 120 does not access a

plurality of memories simultaneously. Rather, the application processor 120 alternately

accesses one memory at a time. Although the main processor 110 attempts to access the

SD card 130 or the NAND flash memory 140, the main processor 110 never accesses

the two memories at the same time. Considering this, the application processor 120 does

not need to have 2 memory interfaces, and having 2 memory interfaces would be a

waste of resource.

Moreover, have 2 memory interfaces causes an increase in physical size, and

consequently a cause for increased price.

[Disclosure]

[Technical Problem] In order to solve the above problems, the present invention aims to provide a

device and a method of sharing a memory interface that can provide the simplest

structure of memory interface, coupling to a plurality of memories.

Another object of the present invention is to provide a device and a method of

sharing a memory interface that can increase the efficiency of an application processor

and reduce the current for operating the application processor, by minimizing the

number of pins included in the memory interface.

It is yet another object of the present invention to provide a device and a

method of sharing a memory interface that can lower the price of an application

processor by simplifying the structure of the memory interface that can be coupled to a

plurality of memories.

It is still another object of the present invention to provide a device and a

method of sharing a memory interface in which more efficient operation is possible by

solving the problem of having to dispose a pin even for a function that is not always

used and by opening the path of an interface to be used and running only an appropriate

logic through sharing the memory interface.

[Technical Solution]

In order to achieve the above objects, an aspect of the present invention

features an application processor that can be coupled to a plurality of memories and/or a digital processing apparatus comprising the application processor.

According to a preferred embodiment of the present invention, the application

processor in a digital processing apparatus, comprising a main processor, an application

processor performing a predetermined additional function in accordance with the

control of the main processor, and a plurality of memories being coupled to the

application processor, comprises: a processing unit, performing the additional function;

a route controller, setting a path for data communication with one of the memories

consisting of a first memory and a second memory coupled to the application processor,

the path being set through a shared memory interface in accordance with the control of

the processing unit; a first memory controller, communicating information with the first

memory through a first memory interface and the route controller; and a second

memory controller, communicating information with the second memory through a

second memory interface and the route controller.

The application processor can further comprise a bus controller, performing

bus control in accordance with the control of the processing unit. The route controller

can set the path for data communication in accordance with a route control signal

received from the bus controller.

In case the number of pins for interfacing with the first memory is n (a natural

number) and the number of pins for interfacing with the second memory is m (a natural

number larger than n), the shared memory interface can comprise k (a natural number) pins between 1 and n-1, the first memory interface can comprise n-k pins, and the

second memory interface can comprise m-k pins.

The first memory interface and the second memory interface can comprise at

least one pin for transmitting at least one of the signals consisting of a clock (CS) signal

and a chip select (CS) signal.

The first memory can be one of the memories consisting of an internal memory

and a removable memory, and the second memory can be the other of the memories

consisting of an internal memory and a removable memory. The removable memory can

be one of the cards consisting of an SD (Secure Digital) card, a CF (Compact Flash)

memory card, an XD (extreme Digital Picture Card), an MS (Memory Stick), and an

MMC (Multi-Media Card).

The digital processing apparatus in accordance with another preferred

embodiment of the present invention can comprise: a main processor; an application

processor, performing a predetermined additional function in accordance with the

control of the main processor; and a plurality of memories, being coupled to the

application processor. The application processor can comprise: a processing unit,

performing the additional function; a route controller, setting a path for data

communication with one of the memories consisting of a first memory and a second

memory coupled to the application processor, the path being set through a shared

memory interface in accordance with the control of the processing unit; a first memory controller, communicating information with the first memory through a first memory

interface and the route controller; and a second memory controller, communicating

information with the second memory through a second memory interface and the route

controller.

In order to achieve the above objects, another aspect of the present invention

features a method of sharing a memory interface, performed in a digital processing

apparatus comprising an application processor, and/or a recorded medium recording a

program for performing the method.

According to a preferred embodiment of the present invention, the method of

sharing a memory interface, performed by an application processor in a digital

processing apparatus, comprising a main processor, an application processor performing

a predetermined additional function in accordance with the control of the main

processor, and a plurality of memories being coupled to the application processor,

comprises: receiving from the main processor a request for accessing a memory; setting

a path for accessing a memory corresponding to the request; and delivering data

received from the main processor to a corresponding memory through the set path. The

path is set through an individual memory interface, independently connected to a

memory corresponding to the request, and a shared memory interface, shared by a

plurality of memories. In case the number of pins for interfacing with a first memory coupled to the

application processor is n (a natural number) and the number of pins for interfacing with

a second memory coupled to the application processor is m (a natural number larger

than n), the shared memory interface can comprise k (a natural number) pins between 1

and n-1 , the first memory interface can comprise n-k pins, and the second memory

interface can comprise m-k pins.

The individual memory interface can comprise at least one pin for transmitting

at least one of the signals consisting of a clock (CS) signal and a chip select (CS) signal.

The first memory can be one of the memories consisting of an internal memory

and a removable memory, and the second memory can be the other of the memories

consisting of an internal memory and a removable memory.

According to another preferred embodiment of the present invention, a

recorded medium tangibly embodies a program, readable by a digital processing

apparatus, of instructions executable by the digital processing apparatus to execute a

method of sharing a memory interface. The program executes the steps of: an

application processor receiving from a main processor a request for accessing a

memory; setting a path for accessing a memory corresponding to the request, wherein

the path is set through an individual memory interface and a shared memory interface,

the individual memory interface being independently connected to a memory

corresponding to the request, the shared memory interface being shared by a plurality of memories; and delivering data received from the main processor to a corresponding

memory through the set path. The digital processing apparatus comprises the main

processor, the application processor performing a predetermined additional function in

accordance with the control of the main processor, and a plurality of memories being

coupled to the application processor.

[Description of Drawings]

Fig. 1 shows a block diagram of a device using a plurality of memories in

accordance with the prior art;

Fig. 2 shows a block diagram outlining an application processor in accordance

with the prior art;

Fig. 3 shows a block diagram outlining a device coupled to a plurality of

memories in accordance with a preferred embodiment of the present invention;

Fig. 4 shows a block diagram outlining an application processor in accordance

with a preferred embodiment of the present invention; and

Fig. 5 illustrates the function of pins (pin muxing table) in a memory interface

in accordance with a preferred embodiment of the present invention.

< Description of Key Elements >

120: Application processor 210: Processing unit

220: Bus controller

230: First memory controller

240: Second memory controller

[Mode for Invention]

The present invention, operative advantages of the present invention, and

objects achieved by embodying the present invention shall be apparent with reference to

the accompanying drawings and the description therein.

Hereinafter, preferred embodiments of the present invention shall be described

in detail with reference to the accompanying drawings. To aid overall understanding of

the present invention, the same reference numbers shall be assigned to the same means,

regardless of the figure number. Moreover, the numbers (e.g., first, second, A, B, etc.)

are only used in the description to identify identical or similar elements.

Moreover, it is evident that the present invention can be applied to any digital

processing apparatus (e.g. a mobile communication terminal having a camera function),

which can perform multiple functions, equivalently or similarly without any restriction.

Furthermore, memories that can be installed in or coupled to a device having a

memory interface sharing function in accordance with the present invention include

internal memories and removable memories. An internal memory refers to a memory, such as a NAND flash memory, installed in a device such that that it is not easily

detachable by the user. A removable memory refers to a memory that is easily

detachable through a socket disposed on a device. Examples of a removable memory

include SD card, CF (compact flash) memory card, XD (extreme digital) Picture Card,

MS (memory stick), and MMC (Multi-Media Card).

However, in order to ease the description and understanding, the following

description will assume that two memories are coupled to the application processor, the

coupled internal memory is a NAND flash memory, and the coupled removable

memory is an SD card.

Fig. 3 is a block diagram outlining the structure of a device, to which a

plurality of memories are coupled, in accordance with a preferred embodiment of the

present invention; Fig. 4 is a block diagram outlining the application processor in

accordance with a preferred embodiment of the present invention; and Fig. 5 is an

illustration of the function of pins (pin muxing table) in a memory interface in

accordance with a preferred embodiment of the present invention.

Referring to Fig. 3, in the device for performing multiple functions, in

accordance with the present invention, the main processor 110 and the application

processor 120 are coupled through a bus for communicating data and/or information,

and the application processor 120 is coupled to one or more memories. A bus refers to a common-purpose electrical route, used for communicating information between

processors or between a processor and a memory.

The application processor 120 can be coupled to the SD card 130 and the

NAND flash memory 140, as illustrated, and has memory interfaces for coupling to the

memories 130 and 140. In other words, the application processor 120 operates the

plurality of memory interfaces as necessary to store multimedia data in any of the

memories or to read and playback the stored data. The memory interface in the

application processor 120 consists of a first memory interface, for communicating

signals independently with a removable memory (e.g. SD card 130), a second memory

interface, for communicating signals independently with an internal memory (e.g.

NAND flash memory 140), and a shared memory interface, selectively being shared for

communicating signals with the removable memory or the internal memory.

Referring to Fig. 4, the application processor in accordance with the present

invention comprises the processing unit 210, a bus controller 220, the first memory

controller 230, the second memory controller 240, and a route controller 410.

The processing unit 210 performs predetermined functions (e.g. MPEG4, 3-D graphics,

and camera), designed to be performed by the application processor 120. The

and delivering the instruction to the bus controller. The processing unit 210 can generate a route control signal, for allowing the bus controller 220 to set a route to a

memory, and send the route control signal to the bus controller. The processing unit 210

can be, for example, a 32-bit processor.

The bus controller 220 performs internal bus control such that the first memory

processing unit 210. The bus controller 220 also controls the route controller 410 such

that the shared memory interface is coupled to a requested memory by the control of the

processing unit 210. Once the route control signal is received from the processing unit

210, the bus controller 220 activates the first memory controller 230 or the second

memory controller 240 in accordance with the route control signal and sends the route

control signal to the route controller 410 such that communication of information with a

corresponding memory becomes possible through the shared memory interface. The

route control signal can be generated by the bus controller 220 using the information (i.e.

interpretation of the instruction received from the main processor 110) delivered from

the processing unit 210. The first memory controller 230 and the second memory

controller 240 can be already activated by default.

The first memory controller 230 sends a control signal to the SD card 130

through the first memory interface. The signal delivered to the SD card 130 through the

first memory interface can be restricted to a signal that is not muxed with other signals,

that is, a signal requiring an independent pin. For example, among the signals (i.e. the data signal, clock (CLK) signal, Command signal, Card Detect signal, Power Control

signal, and Write Protect signal) delivered to the SD card 130, the only signal that is not

muxed with other signals is the CLK signal, and thus only the CLK signal can be set to

be transmitted through the first memory interface. Therefore, the first memory interface

can have at least one pin for the transmission of the CLK signal. In another example of

the external memory being a CF memory card, the first memory interface can have at

least two pins for the unmuxed signals of the chip select (CS) signal and CLK signal. In

another example of the external memory being an XD card or MMC, the first memory

interface can have at least one pin for the unmuxed, CLK signal.

The second memory controller 240 sends a control signal to the NAND flash

memory 140 through the second memory interface. The signal delivered to the NAND

flash memory 140 through the second memory interface can also be restricted to a

signal that is not muxed with other signals. For example, among the signals (i.e. the data

signal, CS signal, CLE signal, ALE signal, REN signal, WEN signal, and WP signal),

the only signal that is unmuxed (can not share the pin) is the CS signal. However, since

the SD card 130 requires only 9 pins, which are less than 14 pins in the NAND flash

memory 140, for interfacing, there are unmuxed signals. For example, the additional,

unmuxed signals can be the CLE signal, ALE signal, REN signal, WEN signal, and WP

signal. The above unmuxed signals can be set to be transmitted to the NAND flash

memory through the second memory interface. Therefore, the second memory interface can have 6 pins for sending the above signals. Of course, in case other memories require

more number of pins, there can be as few as one pin (i.e. the pin for CS signal) in the

second memory interface.

The route controller 410 controls the data flow, depending on which memory is

used by the control of the bus controller 220. The route controller 410 enables the

communication of information between the first memory controller 230 or second

memory controller 240 and the SD card 130 or NAND flash memory 140 by controlling

the shared memory interface. For example, the route controller 410 can select only one

of the signals provided by the first memory controller 230 or second memory controller

240, in accordance with the route control signal received from the bus controller 220,

and output the selected signal through the shared memory interface. The shared memory

interface comprises pins for the signals, which can be muxed, among the signals being

communicated with the memories 130 and 140.

As described above, the application processor in accordance with the present

invention can communicate most signals, except a few signals, through the shared

memory interface although it is coupled to a plurality of memories. The shared memory

interface, which means that the pin is shared, means that the pins shared in the circuit

are commonly connected to the memories 130 and 140. The functions of the pins of the

memory interface in accordance with the present invention are illustrated (in the pin

muxing table) in Fig. 5. As illustrated in Fig. 5, the number of pins to be comprised in the application processor 120 can be reduced to 15 by implementing the shared memory

interface. As described earlier, in the prior art, which has an independent interface for

each memory, a total of 23 pins are needed.

The process of the main processor 110 writing or reading data by accessing the

SD card 130 is briefly described below with reference to Fig. 4. Since the process of the

main processor 110 writing or reading data by accessing the NAND flash memory 140

is similar, its description will not be provided here.

In order to write data in the SD card 130, the main processor 110 sends a

command and the data to the application processor 120. The application processor 120

activates the first memory controller 230 by referencing the interface selection

information included in the command, and sets the route by controlling the route

controller 410 such that the data communication with the SD card 130 becomes possible.

Then, the application processor 120 stores the data, received or being received from the

main processor 110, in the SD card 130 through the set route.

The main processor 110 also reads data from the SD card 130 through the set

route.

The drawings and detailed description are only an example of the present

invention, serve only for describing the present invention, and by no means limit or

restrict the spirit and scope of the present invention. Thus, any person of ordinary skill in the art shall understand that a large number of permutations and other equivalent

embodiments are possible. The true scope of the present invention must be defined only

by the spirit of the appended claims.

[Industrial Applicability]

As described above, the device and method of sharing a memory interface can

provide the simplest structure of memory interface for coupling to a plurality of

memories.

The present invention can also increase the efficiency of the application

processor and reduce the current for operating the application processor, by minimizing

the number of pins included in the memory interface.

Moreover, the present invention can lower the price of the application

plurality of memories.

Furthermore, the present invention makes more efficient operation possible by

logic through sharing the memory interface.

Claims

[CLAIMS]

[Claim 1 ]

An application processor in a digital processing apparatus, the digital

processing apparatus comprising a main processor, an application processor, and a

plurality of memories, the application processor performing a predetermined additional

function in accordance with the control of said main processor, the plurality of

memories being coupled to said application processor, the application processor

comprising:

a processing unit, performing said additional function;

a route controller, setting a path for data communication with one of the

memories consisting of a first memory and a second memory coupled to said

application processor, the path being set through a shared memory interface in

accordance with the control of said processing unit;

a first memory controller, communicating information with said first memory

through a first memory interface and said route controller; and

a second memory controller, communicating information with said second

memory through a second memory interface and said route controller.

[Claim 2]

The application processor of claim 1 , further comprising a bus controller, performing bus control in accordance with the control of said processing unit,

wherein said route controller sets said path for data communication in

accordance with a route control signal received from said bus controller.

[Claim 3]

The application processor of claim 1, wherein, in case the number of pins for

interfacing with said first memory is n (a natural number) and the number of pins for

interfacing with said second memory is m (a natural number larger than n), said shared

memory interface comprises k (a natural number) pins between 1 and n-1, said first

memory interface comprises n-k pins, and said second memory interface comprises m-k

pins.

[Claim 4]

The application processor of claim 1, wherein said first memory interface and

said second memory interface comprise at least one pin for transmitting at least one of

the signals consisting of a clock (CLK) signal and a chip select (CS) signal.

[Claim 5]

The application processor of claim 1, wherein said first memory is one of the

memories consisting of an internal memory and a removable memory, and said second memory is the other of the memories consisting of an internal memory and a removable

memory.

[Claim 6]

The application processor of claim 5, wherein said removable memory is one

of the cards consisting of an SD (Secure Digital) card, a CF (Compact Flash) memory

card, an XD (extreme Digital Picture Card), an MS (Memory Stick), and an MMC

(Multi-Media Card).

[Claim 7]

A digital processing apparatus, comprising:

a main processor;

an application processor, performing a predetermined additional function in

accordance with the control of said main processor; and

a plurality of memories, being coupled to said application processor,

wherein said application processor comprises:

a processing unit, performing said additional function;

a route controller, setting a path for data communication with one of the

memories consisting of a first memory and a second memory coupled to said

application processor, the path being set through a shared memory interface in accordance with the control of said processing unit;

a first memory controller, communicating information with said first memory

through a first memory interface and said route controller; and

a second memory controller, communicating information with said second

memory through a second memory interface and said route controller.

[Claim 8]

The digital processing apparatus of claim 7, further comprising a bus controller,

performing bus control in accordance with the control of said processing unit,

wherein said route controller sets said path for data communication in

accordance with a route control signal received from said bus controller.

[Claim 9]

The digital processing apparatus of claim 7, wherein, in case the number of

pins for interfacing with said first memory is n (a natural number) and the number of

pins for interfacing with said second memory is m (a natural number larger than n), said

shared memory interface comprises k (a natural number) pins between 1 and n-1, said

first memory interface comprises n-k pins, and said second memory interface comprises

m-k pins.

[Claim 10]

The digital processing apparatus of claim 7, wherein said first memory

interface and said second memory interface comprise at least one pin for transmitting at

lease one of the signals consisting of a clock (CLK) signal and a chip select (CS) signal.

[Claim 11 ]

The digital processing apparatus of claim 7, wherein said first memory is one

of the memories consisting of an internal memory and a removable memory, and said

second memory is the other of the memories consisting of an internal memory and a

removable memory.

[Claim 12]

The digital processing apparatus of claim 11, wherein said removable memory

is one of the cards consisting of an SD (Secure Digital) card, a CF (Compact Flash)

memory card, an XD (extreme Digital Picture Card), an MS (Memory Stick), and an

MMC (Multi-Media Card).

[Claim 13]

A method of sharing a memory interface, performed by an application

processor in a digital processing apparatus, the digital processing apparatus comprising a main processor, an application processor, and a plurality of memories, the application

processor performing a predetermined additional function in accordance with the

control of said main processor, the plurality of memories being coupled to said

application processor, the method comprising:

receiving from said main processor a request for accessing a memory;

setting a path for accessing a memory corresponding to said request; and

delivering data received from said main processor to a corresponding memory

through said set path,

wherein said path is set through an individual memory interface and a shared

memory interface, the individual memory interface being independently connected to a

memory corresponding to said request, the shared memory interface being shared by a

plurality of memories.

[Claim 14]

The method of sharing a memory interface of claim 13, wherein, in case the

number of pins for interfacing with a first memory coupled to said application processor

is n (a natural number) and the number of pins for interfacing with a second memory

coupled to said application processor is m (a natural number larger than n), said shared

memory interface comprises n-k pins, and said second memory interface comprises m-k pins.

[Claim 15]

The method of sharing a memory interface of claim 13 or claim 14, wherein

said individual memory interface comprises at least one pin for transmitting at least one

of the signals consisting of a clock (CLK) signal and a chip select (CS) signal.

[Claim 16]

The method of sharing a memory interface of claim 14, wherein said first

memory is one of the memories consisting of an internal memory and a removable

memory, and said second memory is the other of the memories consisting of an internal

memory and a removable memory.

[Claim 17]

A recorded medium tangibly embodying a program of instructions executable

by a digital processing apparatus to execute a method of sharing a memory interface, the

program readable by said digital processing apparatus, the program executing the steps

of:

an application processor receiving from a main processor a request for

accessing a memory; setting a path for accessing a memory corresponding to said request, wherein

said path is set through an individual memory interface and a shared memory interface,

the individual memory interface being independently connected to a memory

corresponding to said request, the shared memory interface being shared by a plurality

of memories; and

delivering data received from said main processor to a corresponding memory

through said set path,

wherein said digital processing apparatus comprises said main processor, said

application processor, and a plurality of memories, the application processor performing

a predetermined additional function in accordance with the control of said main

processor, the plurality of memories being coupled to said application processor.