Electrical computers and digital processing systems: memory – Storage accessing and control – Control technique
Reexamination Certificate
1998-12-07
2001-05-15
Yoo, Do Hyun (Department: 2187)
Electrical computers and digital processing systems: memory
Storage accessing and control
Control technique
C711S159000, C711S154000, C711S208000, C709S241000
Reexamination Certificate
active
06233664
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a swapping apparatus and method, and more particularly, to an apparatus and method for swapping program code and data between a main memory and an auxiliary memory, and a web video phone adopting the apparatus.
2. Description of the Related Art
Swapping includes the exchange of contents stored in a main memory with contents stored in an auxiliary memory. Here, swapping includes swap-in and swap-out. Swap-in is the transfer of a program having high priority from the auxiliary memory to the main memory. Swap-out is the transfer of a program having low priority from the main memory to the auxiliary memory.
FIG. 1
is a block diagram of a conventional web video phone which does not adopt a swapping apparatus.
Referring to
FIG. 1
, a DRAM
10
, being a type of main memory, has a basic program code region
102
for storing a real time OS (operating system) code and a main menu, and a program code and data region
104
for swapping application programs in a flash memory
12
.
The flash memory
12
, being a type of auxiliary memory, stores application programs (
122
,
124
,
126
, . . . and
128
) static-linked to an OS library. In the web video phone of
FIG. 1
, all application programs stored in the flash memory
12
are downloaded into the DRAM
10
all at once in the power starting sequence.
However, the web video phone of
FIG. 1
has the following problems.
First, since the application programs static-linked to the OS library cannot be separated, they are downloaded into the DRAM
10
all at once, which requires a DRAM having a large capacity. That is, the DRAM
10
must have a capacity of at least 4M byte to download four application programs, each of 1M byte size from the flash memory
12
to the DRAM
10
. Second, in the static linking of application programs stored in the flash memory, even when only one application program is changed, the other application programs must be recompiled and linked, which results in difficult management of the application programs.
SUMMARY OF THE INVENTION
To solve the above problems, it is an objective of the present invention to provide an apparatus and method of swapping between main and auxiliary memories for swapping program code and data into a predetermined region of a DRAM, for only an application program, to be used for execution by an input unit, from among a plurality of application programs stored in an auxiliary memory, and a web video phone adopting the apparatus.
Accordingly, to achieve the above objective, there is provided an apparatus for swapping program code and data between a main memory and an auxiliary memory, comprising: an auxiliary memory for storing a plurality of application programs including program codes and data; a virtual address table for storing a start address of each application program stored in the auxiliary memory; a main memory having a program code region and a data region for storing a program code downloaded from the auxiliary memory and data swapped from the auxiliary memory; and a swapping controller for controlling the program codes of the programs to be downloaded into the program code region of the main memory with reference to addresses stored in the virtual address table, and controlling the swapping between the data of the programs and data stored in the data region of the main memory, in response to a request input via a user interface to execute the application programs.
To achieve the above objective, there is provided a method of swapping program code and data between a main memory and an auxiliary memory, comprising the steps of: (a) determining whether the program code of an application program to be executed exists in a program code region of the main memory; (b) downloading a program code stored in the auxiliary memory into a program code region of the main memory, when it is determined in step (a) that the program code does not exist in main memory; (c) swapping data of an application program stored in the auxiliary memory for data stored in the data region of the main memory; and (d) loading to a program counter a start address of the program downloaded into the main memory in step (b) and executing the program code from the start address.
To achieve the above objective, there is provided a web video phone wherein program code and data of a DRAM and a flash memory are swapped, comprising: a key input unit for inputting a command of execution of an application program; a flash memory for storing application programs including at least a video phone using the H.324 protocol, an Internet phone using the H.323 protocol, a web browser, an e-mail program, and a personal information management system (PIMS); a DRAM including a program code region and a data region for storing program codes downloaded from the flash memory and data swapped from the flash memory; and a main processor for controlling the program code of each application program stored in the flash memory to be stored in the program region of the DRAM and controlling the swapping between the data of each application program stored in the flash memory and the data stored in the data region of the DRAM, in response to an execution command of an application program input through the key input unit.
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Namazi Mehdi
Samsung Electronics Co,. Ltd.
Sughrue Mion Zinn Macpeak & Seas, PLLC
Yoo Do Hyun
LandOfFree
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