Electrical computers and digital processing systems: memory – Storage accessing and control – Specific memory composition
Reexamination Certificate
2001-11-28
2004-06-29
Sparks, Donald (Department: 2187)
Electrical computers and digital processing systems: memory
Storage accessing and control
Specific memory composition
C711S159000, C711S169000, C710S105000, C710S313000
Reexamination Certificate
active
06757783
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to a portable storage medium using a flash memory and, more particularly, to a portable storage medium based on universal serial bus (USB) standard and a control method therefore, which can be simply recognized and driven by a host computer through USB and UFI (USB floppy interface), facilitates the extension of the flash memory capacity and ensures high speed of data writing.
2. Description of the Related Art
Conventional portable storage media, which supplement a fixed type storage medium such as a hard disk. Include a floppy disk, CD-ROM and zip drive disk, etc. However, a host computer using this portable storage medium must have an additional drive for the medium. The floppy disk is not widely used because of its small storage capacity. The CD-ROM of large capacity has a weakness that its surface is easily damaged.
Accordingly, a portable storage medium using a flash memory such as a flash drive having large storage capacity has been recently developed and being rapidly popularized. It is easily connected with the host computer and employs USB standard that guarantees high rate of data transmission. The USB standard is a computer port standard proposed by Intel, Microsoft and Compaq in order to develop plug and play. It does not require rebooting of the host computer when a peripheral device is connected to the host computer and ensures fast transmission rate, 12 Mb/s, for example.
Meantime, U.S. Pat. No. 6,148,354 entitled “Architecture for a universal serial bus-based PC flash disk”, U.S. Pat. No. 6,012,103 entitled “Bus interface system and method”, and Korea Patent No. 2001-35042 entitled “Portable storage medium using USB interface and flash memory” disclose the configuration of the USB-based portable storage medium and bus interfacing method.
FIG. 1
is a block diagram that roughly illustrates the configuration of the conventional USB-based portable storage medium. Reference numeral
10
represents a host computer having an operating system applying USB standard protocol, and
11
denotes a USB port through which a USB-based peripheral device is physically connected to the host computer. Reference numeral
12
designates a USB host controller for detecting a peripheral device being connected to the USB port
11
and controlling transmission and reception of data between the host computer
10
and the peripheral device based on the USB standard.
Reference numeral
13
denotes an inner storage medium of the host computer
10
, such as hard disk, which has the operating system of the host computer
10
and a predetermined client driver. The client driver is provided by a USB flash drive manufacturer, which will be described below. A microprocessor (not shown) of the host computer
10
controls the entire operation of the host computer according to the operating system and the operation routine of the client driver.
The host computer
10
in
FIG. 1
may be a computer device having the operating system installed the inner storage medium thereof, such as personal computer, servers and mobile communication terminal. The operating system is a general operating system such as Window 95, 98. ME, XP, MAC OS, including USB standard protocol.
The operating system recognizes the peripheral device connected to the host computer
10
to load a corresponding driver, assigns a USB bus address and system resource to the peripheral device, and operates the USB host controller
12
according to the USB standard. The client driver is loaded by the operating system to prepare a USB flash drive connected to the USB port
11
, which will be described below, for operation. In addition, the client driver is compatible with firmware stored in the inner storage medium of the USB flash drive to execute various driving commands for operation of the USB flash drive.
Reference numeral
20
designates the USB flash drive containing a nonvolatile memory that is connected with the USB port
11
of the host computer
10
to store data transmitted from the host computer
10
, and write, read and delete data through the host computer
10
. Reference numeral
21
denotes a USB connector connected with the USB port
11
of the host computer
10
physically, and
22
represents a memory for storing data sent from the host computer
10
, which includes at least one flash memory
221
~
22
n
that is a nonvolatile memory. The flash memory
221
~
22
n
has two kinds of NOR and NAND types. The USB flash drive
20
employs the cheap NAND type flash memory.
In
FIG. 1
, reference numeral
23
represents a decoder for decoding predetermined memory address information inputted from a processor that will be described below to output a chip select signal for selectively driving the flash memory
221
~
22
n
. Reference numeral denotes a program storage in which a USB flash drive driving program, that is, firmware, is stored, and
25
is the processor for controlling the entire operation of the USB flash drive
20
according to the driving program of the program storage
24
.
Hereinafter, the operation of the conventional USB-based portable storage medium constructed as above will be explained.
First of all, when the USB flash drive
20
is connected to the USB port
11
of the host computer
10
to be provided with operation power, the processor
25
in
FIG. 1
initializes the flash memory of
221
~
22
n
of the memory
22
according to the operation program of the program storage
24
. In addition, the processor
25
transmits predetermined device descriptor information including a manufacturer ID and product ID to the host computer
10
at the host computer's request for device identification information to inform the host computer of initialization of the operation of the USB flash drive
20
. The device descriptor information is basic information based on the USB standard, by which the host computer
10
recognizes the USB flash drive
20
.
The host computer
10
receives the device descriptor information through the USB host controller
12
, and then inquires peripheral device driver information contained in the operating system to confirm if a driver corresponding to the manufacturer ID and product ID is registered. Here, when the driver of the USB flash drive
20
is confirmed as registered, the host computer
10
loads the client driver according to the operation routine of the operating system and, simultaneously, allocates a USB bus address and system resource to the USB flash drive
20
to prepare its operation.
When it is determined that the driver of the USB flash drive
20
is not registered, on the other hand, the host computer
10
displays a request for installation of the client driver through a monitor (not shown). If a user installs the client driver provided by the manufacturer, the host computer
10
assigns the USB bus address and system resource to the USB flash drive
20
to prepare its operation. Then, the user operates the host computer
10
to store data in the USB flash drive
20
, read or delete data from the host computer, or copy data into the host computer
10
. At this time, the operating system of the host computer
10
and the operation program of the client driver and USB flash drive
20
work with each other to provide operation routines of data writing/reading/deletion operations of the flash memory
221
~
22
n.
With the conventional USB flash drive
20
, the client driver of corresponding manufacturer should be installed in the host computer
10
for the initial operation thereof. In case where a user uses a plurality of host computers, the client driver should be installed in each of them in terms of the characteristic of the portable storage medium.
Furthermore, with the NAND flash memory
221
~
22
n
used in the USB flash drive
20
, data is read or written in pages of the flash memory when it performs “write” or “read” instruction. In addition, before data is written in an arbitrary page, it is required that the entire page of the block including the corresponding page is de
Daesung EC&P Co., Ltd.
Lilling & Lilling P.C.
Peugh Brian R.
Sparks Donald
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