United States Patent 55
`6,078,541
`Kitagawaet al.
`Jun. 20, 2000
`Date of Patent:
`[45]
`
`Patent Number:
`
`[11]
`
`US006078541A
`
`[54] DEVICE CONTROLLER HAVING VOLATILE
`AND NON-VOLATILE MEMORY FOR
`STORAGE OF DECOMPRESSED AND
`COMPRESSED DATA
`
`.
`
`[75]
`
`OTHER PUBLICATIONS
`Doi, M., et ‘ Developmentof a RotaryHead Digital Audie
`Tape Recorder (R-DAT), Sanyo Technical Review vol. 19
`No. 2, pp. 3-17, Aug. 1997.
`Primary Examiner—Richard Elms
`Inventors: Masayuki Kitagawa, Koji Tsuboi,
`Assistant Examiner—Anh Phung
`both of Irvine, Calif.
`
`
`Att Agent,orFirm—Knobbe Martens Olson & B
`
`[73] Assignee: Mitsumi Electronics Co., Ltd., Japan ELEN SSS
`
`.
`
`[21] Appl. No.: 09/067,706
`
`[57]
`
`ABSTRACT
`
`[22]
`
`Filed:
`
`Apr. 28, 1998
`
`4
`[ST]
`Tint, Ceceeceeseceeenseeneennenneensees GLIC 8/00
`
`[52]
`- 365/230.01; 365/230.08
`[58] Field of Search oe. 365/230.08, 230.01,
`365/185.01, 185.33, 185.08
`.
`References Cited
`U.S. PATENT DOCUMENTS
`
`[56]
`
`§,194,995
`3/1993 Severtson et al. cece 360/48
`5,218,487
`6/1993 Richmond sess
`seeeees 360/27
`
`eeeane <fo0n comston . al serteeteesensee
`conesSatesta
`
`we
`.....
`3530,
`chieve et al.
`.
`
`9/1996 Kojimaet al. cscsssscssssssseeneen 369/60
`5,555,229
`
`w 395/430
`4/1997 Kim etal. ....
`5,623,623
`9/1997 Saliba csecsessssssssseesssesssesesssssesees 395/438
`5,671,389
`
`11/1998 Gotoh wesc
`ceeeeneee 395/712
`5,838,981
`5,850,562 12/1998 Crumpetal. oo. eeeeeeeeee 395/800
`
`A device controller for controlling the operation of the drive
`device. The controller includes a microprocessor, a volatile
`memory, and a non-volatile memory. The non-volatile
`memory stores an uncompressed decompression program
`and a compressed device operating program. The micropro-
`cessor automatically decompresses the device operating
`program by executing the decompression program and
`stores the decompressed device operating program into the
`volatile memory whenthe drive is powered up orreset, The
`microprocessor then executes the device operating program
`stored in the volatile memory which hasa faster data access
`rate than the non-volatile memory. As the device operating
`program is stored in a compressed form, the size of the
`_
`:
`.
`see
`:
`:
`NOR voratile theethy isminimized. theae ene
`HAY als Tecuce ine size Of
`@ non-volatile memory tor
`_—«*Storing data used in a device controller.
`
`37 Claims, 3 Drawing Sheets
`
`
`
`po
`
`cm
`|
`
`—
`
`LO05
`
`
`
`DRIVE
`DEVICE
`105
`
`
`
`HOST
`COMPUTER
`103
`
`
`
`COMPRESSED
`DEVICE
`OPERATING
`PROGRAM
`(OR DIGITAL
`INFORMATION)
`
`
`
`
`
`203
`
`26)
`
`
` DATA BUFFER
`
`
`
`
`
`DECOMPRESSION
`J-277
`DECOMPRESSED
`
`
`DEVICE
`
`LOADER
`
`OPERATING
`PROGRAM
`PROGRAM
`
`
`VOLATILE MEMORY
`
`NetApp
`
`Exhibit1010
`
`Page 1
`
`NetApp Exhibit 1010 Page 1
`
`

`

`HOSTCOMPUTER
`
`Jun. 20, 2000
`
`Sheet 1 of 3
`
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`L909
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`Lu
`az
`Oo
`oO
`
`U.S. Patent
`
`105
`
`10/7
`
`103
`
`6,078,541
`
`FIG.1
`
`NetApp
`
`Exhibit1010
`
`Page2
`
`NetApp Exhibit 1010 Page 2
`
`

`

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`U.S. Patent
`
`Jun. 20, 2000
`
`Sheet 2 of 3
`
`6,078,541
`
`JAG
`
`JIIAIG
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`GOl
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`JOIAIG
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`Wvu90ud
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`WW19IdYO)
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`<0l
`
`NetApp
`
`Exhibit1010
`
`Page 3
`
`NetApp Exhibit 1010 Page 3
`
`
`

`

`U.S. Patent
`
`Jun. 20, 2000
`
`Sheet 3 of 3
`
`6,078,541
`
`JO7
`
`
`COMPRESSED
`
`PROGRAM AVAILABLE
`IN NON-VOLATILE
`
`MEMORY
`?
`
`DECOMPRESSION
`
`HOST COMMAND
`RECEIVED
`?
`
`YES
`
`COMPRESSED
`PROGRAM
`RECEIVED
`?
`
`NO
`
` SOS
`
` FROM 379
`- HOST COMMAND
`
`
`
` PROGRAM
`
`
`
`VOLATILE MEMORY
`
`RECEIVED
`?
`
`YES
`
`JIS
`
`COMPRESSED
`
`RECEIVED
`?
`
`ES
`
`J/7
`
`RECEIVE AND
`STORE INTO
`
`JT1
`
`TRANSFER EXECUTION TO
`DRIVE OPERATING PROGRAM
`
`JI19
`
`TRANSFER INTO
`NON—VOLATILE MEMORY
`
`FIG. 3
`
`NetApp
`
`Exhibit1010
`
`Page 4
`
`NetApp Exhibit 1010 Page 4
`
`

`

`6,078,541
`
`1
`DEVICE CONTROLLER HAVING VOLATILE
`AND NON-VOLATILE MEMORY FOR
`STORAGE OF DECOMPRESSED AND
`COMPRESSED DATA
`
`BACKGROUND OF THE INVENTION
`
`1. Field of the Invention
`
`The present invention relates to a memory system having
`a non-volatile and a volatile memory. More particularly, the
`present invention relates to a memory system that stores a set
`of executable codes in a volatile memory and decompresses
`it into a non-volatile memory for execution.
`2. Description of the Related Technology
`A data storage device, such as a digital audio tape (DAT)
`drive, is composed of a drive device mechanism including
`read/write heads and a device controller for controlling the
`drive device according to instructions from a connected host
`computer such as a personal computer (PC). The device
`controller monitors and controls the operation of the entire
`drive device by running a device operating program. The
`device controller thus generally includes a microprocessor
`for running the program code, a non-volatile memory for
`persistently storing the program code, a volatile memory for
`temporarily storing program code and data, and buslinesto
`allow data communication among the components.
`The non-volatile memory of the device controller stores
`the device operating program and,
`in addition, a loader
`program. A flash memory is an important type of non-
`volatile memory since data stored in a flash memory can be
`rewritten. Thus, by using a flash memory, revisions to the
`device operating program may be updated with the device
`controller.
`
`The volatile memory of the device controller has a buffer
`to temporarily store data whichis to be written to the storage
`device or to be transferred to the host computer. The volatile
`memory also has an area for storing the device operating
`program and data during the execution.
`In DAT drive
`controllers, the volatile memoryis typically implemented by
`a dynamic random access memory (DRAM).
`When power to a data storage device is turned on, the
`microprocessor automatically executes the loader program
`stored in the nonvolatile memory, and copies the device
`operating program from the nonvolatile memory to the
`volatile memory. Then the microprocessor runs the device
`operating program to monitor and control the operation of
`the drive.
`
`Because of the increasing needfor fine controlof the drive
`software, as well as the need for providing greater function-
`ality in operating the drive, device operating programs have
`continued to grow. Naturally, this increase in program size
`requires a larger non-volatile memory to store it. It may,
`however, not be practical
`to use a larger non-volatile
`memory because of the increased product cost. Therefore,
`there is a need to restrict the size of the expensive non-
`volatile memory whichis used for storing programsin a data
`storage device.
`SUMMARY OF THE INVENTION
`
`The aforementioned needsare satisfied by several aspects
`of the present invention.
`The present invention provides a device controller using
`a relatively small size of non-volatile memory for storing
`device operating programs.
`The present invention also provides a memory system
`having a reduced size of a non-volatile memory for storing
`data inevitably used in the system.
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`One aspect of the present invention provides a device
`controller for controlling operation of a device. The con-
`troller comprises: a volatile memory; a non-volatile memory
`storing a compressed program; and a microprocessorin data
`communication with the volatile memory and the non-
`volatile memory for executing programs, wherein the micro-
`processor decompresses the compressed program andstores
`the decompressed program into the volatile memory for
`execution.
`
`Anotheraspect of the present invention provides a method
`for executing a compressed program in a device controller
`for controlling a peripheral device connected to a host
`computer through the controller, the controller comprising a
`volatile memory, a non-volatile memory, and a micropro-
`cessor in data communication with the volatile memory and
`the non-volatile memory for executing programs, and the
`non-volatile memory storing an uncompressed decompress-
`ing program. The method comprises: checking automati-
`cally if the compressed program is available in the non-
`volatile memory when the controller is powered up orreset;
`executing the decompression program to decompress the
`compressed program when the compressed program is avail-
`able and storing the decompressed program into the volatile
`memory; and executing the decompressed program.
`A further aspect of the present
`invention provides a
`memory system comprising a volatile memory; a non-
`volatile memory storing compressed electronic information
`and an uncompressed decompression program for decom-
`pressing the compressed electronic information; and a
`microprocessor in data communication with the volatile
`memory and the non-volatile memory for executing
`programs, wherein the microprocessor decompresses the
`compressed electronic information and stores the decom-
`pressed electronic information into the volatile memory for
`use.
`
`These and other features of the present invention will
`become more fully apparent from the following description
`and claims.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`illustrating the
`FIG. 1 is a schematic block diagram,
`interrelation of a device controller of the present invention
`with a host computer and a drive device.
`FIG. 2 is a partial block diagram of the DAT drive,
`illustrating the memory system of a device controller of one
`embodiment of the present invention.
`FIG. 3 is a flowchart, illustrating the loading, storing, and
`updating of a device operating program of one embodiment
`of the present invention.
`DETAILED DESCRIPTION OF THE DRAWINGS
`
`The size of non-volatile memory required to store a
`device operating program is reduced by storing the device
`operating programs in a compressed form as will be
`described below for one embodiment of the present inven-
`tion.
`
`Referring to FIG. 1, a device controller 101 of the present
`invention permits a host computer 103 to communicate data
`to and from a drive device 105. The device controller 101
`monitors and controls the entire operation of the drive
`device 105 by running a device operating program whichis
`stored in a non-volatile memoryof the device controller 101
`in a compressed form. The device controller 101 receives
`instructions from the host computer 103 to operate the
`device drive 105. The device controller 101 also communi-
`cates the status of the drive device 105 with the host
`
`computer 103.
`
`NetApp
`
`Exhibit1010
`
`Page5
`
`NetApp Exhibit 1010 Page 5
`
`

`

`6,078,541
`
`3
`The device controller 101 may be a controller for any
`peripheral device of a host computer 103. The device
`controller 101 may,for instance, be a controller for a storage
`device of a host computer 103, such as a controller for a
`DAT drive. The host computer 103 may be any general
`purpose computer such as an IBM compatible or Apple
`Macintosh personal computer, a workstation available from
`Sun Microsystems, Inc., IBM, Hewlett Packard, or Silicon
`Graphics,
`Inc., a minicomputer available from Digital
`Equipment Corporation, or a mainframe available from
`IBM. The host computer 103 may also be a special purpose
`computer. The device controller 101 may be connected to
`the host computer 103 through one of the extended slots in
`the host computer 103. The device controller 101 also may
`be integrated into a single package with the drive device
`105.
`FIG. 2 shows one embodiment of a DAT drive controller
`which comprises a non-volatile memory 201, a volatile
`memory 203, and a microprocessor 205. A bus line 207
`interconnects the non-volatile memory 201,
`the volatile
`memory 203, and the microprocessor 205. The bus line 207
`mayalso electrically connect the device controller 101 to the
`host computer 103 and the drive device 105 either directly
`or indirectly via the use of other integrated circuits.
`The non-volatile memory 201 stores a loader program
`209, a decompression program 211, and a device operating
`program 213. The non-volatile memory 201 may be
`writable, so that future revisions of programs may be stored
`in the device controller. The writable non-volatile memory
`may be a flash memory,electrically erasable programmable
`read only memory (EEPROM), any magnetically recordable
`media, or an internal writable ROM of a microprocessor.In
`one embodiment,
`the writable non-volatile memory is
`advantageously a flash memory. A flash memory such as
`Am29F200S available from Advanced Micro DevicesInc.,
`and M29F200B available from SGS-Thomson Microelec-
`tronics could be utilized. The device operating program 213
`is stored in a compressed form so that
`the size of the
`non-volatile memory 201 is minimized. The loader program
`209 and the decompressing program 211, on the other hand,
`are stored in an uncompressed form so that the micropro-
`cessor 205 may run them as is, without decompression.
`The volatile memory 203, which may be a DRAM,an
`SRAM oran internal RAM of a microprocessor, functions as
`a main memoryfor storing an executable copy of the device
`operating program 215, 1.¢., the copy created after decom-
`pression of the compressed device operating program 213.
`The volatile memory 203 thus stores the decompressed
`device operating program 215 and data generated duringits
`execution. The volatile memory 203 has a buffer 217 for
`buffering data transfer between the drive device 105 and the
`host computer 103. Examples of the volatile memory 203
`are HM5118116OBJ available from Hitachi Co., Ltd.,
`TCS5118165CJ available from Toshiba Corporation, and
`uPD421816OLEavailable from NEC Co., Ltd. The volatile
`memory 203 will typically have a higher data access rate
`than the non-volatile memory 201 since the program is
`fetched and executed from the volatile memory 203 rather
`than the non-volatile memory 201. For example, the access
`cycle time of Am29F200S, non-volatile memory, and
`HM51181160BJ, volatile memory, are respectively 120 ns
`and 60 ns.
`
`The microprocessor 205 is required to run the loader
`program 209 and the decompression program 211 stored in
`the non-volatile memory 201 and the decompressed device
`operating program 215 which is stored in the volatile
`memory 203 after running the decompression program 211.
`
`4
`The microprocessor 205 may be any conventional general
`purpose or single-chip or multi-chip processor such as
`HD6417604SF28 available from Hitachi Co., Ltd.,
`uPD703001GC-25-7EA available from NEC Co., Ltd., and
`MC68331 and MC68332 from Motorola Inc.
`
`The compressed device operating program 213 is com-
`pressed in a format which the decompression program 211
`can decompress. Any conventional compression/
`decompression algorithms, such as Lempel-Ziv, Lempel-
`Ziv-Huffman, and Lempel-Ziv-Welch, could be utilized. In
`one embodiment, a Lempel-Ziv algorithm is advantageously
`used in the compression/decompression. As the decompres-
`sion program 211, GZIP available from GZIP Organization
`(http://www.gzip.org) run by Free Software Foundation Inc.
`and PKZIPavailable from Pkware Inc. are examples.
`The compressed device operating program 213 may be a
`self-executing file which can be decompressed and executed
`without
`the decompression program 211.
`If the device
`operating program 213 is compressed in a self-executable
`format, the decompression program 211 is not required and
`the size of the non-volatile memory 201 can be reduced. Any
`conventional self-executable format can be utilized.
`
`Whenthe device controller 101 is powered up orreset, the
`instructions of the loader program 209 are fetched and
`executed by the microprocessor 205. At some point, control
`is passed from the loader program 209 to the decompression
`program 211. Then, the compressed device operating pro-
`gram 213 is decompressed by the execution of the decom-
`pression program 211 under the control of the loader pro-
`gram 209. As the decompression proceeds,
`the
`decompressed device operating program 215 is stored a
`fragment at a time into the volatile memory 203. At some
`point, control passes to the decompressed device operating
`program stored in the volatile memory. The decompressed
`device operating program 215 is fetched and run by the
`microprocessor 205 to monitor and control the operation of
`the drive device 105. For example,
`the device operating
`program 215 controls the data read/write, data transfer
`between the host computer 103 and the drive device 105,
`data search, drum rotation, tape movement by rotating the
`capstan, or tape positioning in accordance with instructions
`from the host computer 103. The operation of one embodi-
`ment of the present invention will be discussed below in
`reference to FIG. 3.
`
`FIG. 3 showsan operational flowchart for the control of
`receiving, updating, and decompressing the compressed
`device operating program 213 by the loader program 209 in
`one embodiment of the present invention.
`When the drive device 105 is powered on, the micropro-
`cessor 205 automatically fetches the loader program 209
`from the non-volatile memory 201 and starts to run the
`loader program 209 at a state 301. The loader program 209,
`at a state 303, checks whether the compressed device
`operating program 213 is available in the non-volatile
`memory 201 or not. If the compressed device operating
`program 213 is stored in the non-volatile memory 201, the
`loader program 209 fetches the decompression program 211
`from the non-volatile memory 201 and executesit to decom-
`press the compressed device operating program 213 at a
`state 305. As the decompression program 211 decompresses
`the compressed device operating program 213, the micro-
`processor 205 stores the decompressed program into an area
`of the volatile memory 203 reserved for the decompressed
`device operating program 215. When the decompression is
`completed, the microprocessor 205 is ready to execute the
`decompressed device operating program 215 to operate the
`drive device 105 according to instructions from the host
`computer 103.
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`NetApp
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`Exhibit1010
`
`Page6é
`
`NetApp Exhibit 1010 Page 6
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`

`

`6,078,541
`
`5
`At a state 307, the loader program waits for an instruction
`from the host computer 103 for a specific command function
`such as read or write data from or onto a magnetic tape
`loaded in the drive device 105, position a specified location
`on the tape, search a specific data, or read a specified size of
`data. When a commandis received from the host computer
`103, the loader program 209 checksif the host command is
`to download a compressed device operating program at a
`state 309. If the host command is not
`to download a
`compressed program, the loader program 209 transfers the
`execution to the device operating program at a state 311. The
`device operating program 215 then decodes the instruction
`from the host computer 311 and starts to control the opera-
`tion of the drive device 105.
`
`If the compressed device operating program 213 is not
`found in the non-volatile memory 201 at the state 303, the
`loader program 209 waits for a compressed device operating
`program 213 from the host computer 103 at a state 313.
`When a command comes from the host computer 103, it is
`determined whether or not a compressed program is
`received at a state 315. If the received instruction is the
`compressed device operating program, the loader program
`209 proceeds to the state 317. Otherwise, the loader program
`209 goes back to the state 313 to wait on a command from
`the host computer 103.
`When the received command is determined to be a
`compressed device operating program 213 at either of the
`states 309 or 315, the compressed program 213 is received
`and stored into the non-volatile memory 201.
`In one
`embodiment, the compressed program 213 is received and
`temporarily stored in the data buffer 217 of the volatile
`memory 203 first at a state 317, and it is transferred,at a state
`319, to the non-volatile memory 201after the entire program
`has been received. This is because receiving the program by
`using the faster volatile memory 203 reduces the time that
`the host computer 205 is busy with the transfer process.
`When the transfer of the compressed device operating
`program 213 is completed at
`the state 319,
`the loader
`program 209 goesto the state 305 to decompress the newly
`received program 213. The compressed device operating
`program 213 is decompressed, and the loader program 209
`continues the flow from there as described above.
`
`A comparison can be made of memory sizes, space
`occupancies, and costs of non-volatile memory required in
`a DAT drive controller of one embodiment of the present
`invention and the prior art. Assumethat the device operating
`program 213 is initially 611 kB. The device operating
`program 213 is compressed by using GZIP.COM which
`utilizes Lempel-Ziv algorithm, which reducesthe size of the
`program to 221 kb. Provided that the sizes of the decom-
`pression program 211 and the loader program 209 are 2 kb
`and 12 kb, respectively. 235 kb (22142412)ofthetotal size
`of the programs requires one 256 kb flash memory as the
`non-volatile memory 201 which occupies 1x(0.6x1.1)
`square inches on a printed circuit board of a DAT drive and
`costs about U.S. $10 in today’s prices. On the other hand, the
`611 kb of non-compressed device operating program and a
`12 kb of loader require three 256 kb flash memories which
`occupy 3x(0.6x1.1) square inches on a printed circuit board
`of a DATdrive and costs about U.S. $30.
`
`invention stores the
`One embodiment of the present
`device operating program in the non-volatile memory in a
`compressed form. This reduces the memory size of the
`non-volatile memory required to persistently store the drive
`operating program as well as reducing the space occupancy
`of the non-volatile memory in a printed circuit board.
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`Additionally, since the device operating program is stored in
`a compressed form,
`it
`takes less time to download the
`program from the host computer in this embodimentof the
`present invention than a device controller storing the pro-
`gram in an uncompressed form.
`Another embodiment of the present invention is directed
`to a memory system for storing electronic information in a
`compressed form and for decompressing the electronic
`information for use. FIG. 2 also shows another embodiment
`of the present invention as a memory system which com-
`prises a non-volatile memory 201, a volatile memory 203, a
`microprocessor 205, and a bus line 207. In this embodiment,
`the bus line 207 is not necessarily connected to the host
`computer 103 or drive device 105.
`The non-volatile memory 201 stores a loader program
`209, a decompression program 211, and digital information
`213. The term “digital information” may include any data or
`program code which can be stored in a digital form. The
`loader program 209 and the decompression program 211 are
`stored in an uncompressed form, so that the microprocessor
`205 can retrieve them without decompression. The digital
`information 213 is stored in a compressed form to minimize
`the memory size of the non-volatile memory 201. The
`microprocessor automatically executes the loader program
`209 to control the operation of the memory system whenthe
`power is turned on. The loader program 209 runs the
`decompression program 211 to decompress the compressed
`digital information 213 and store the decompressed digital
`information 213 into the volatile memory 203. The digital
`information 213 may include programsto be executed by the
`microprocessor 205 and data to be used during the execution
`of the programs.
`The non-volatile memory 201 may further store a com-
`pression program (not shown) in an uncompressed form.
`The microprocessor 205 executes the compression program
`whenthe programsordata stored in the volatile memory 203
`are updated and need to be persistently stored into the
`non-volatile memory 201. Thus, in such an embodiment, the
`non-volatile memory 201 is writable. However, the non-
`volatile memory 201 need not be a writable memory when
`there is no need to recompress digital information and save
`it.
`
`The non-volatile memory 201 may be a magnetic storage
`device such as a magnetic disk and a magnetic tape, a solid
`state storage device such as a flash memory, a ROM,a
`PROM,an EEPROM,an FRAM,aninternal writable ROM
`of a microprocessor, and an optical storage device such as a
`CD-ROM,
`a CD-ROM-Recordable (CD-R), and a
`CD-Recordable and Writable (CD-RW). The volatile
`memory 203 functions as a main memory as discussed
`above. Examples of the volatile memory 203 are a DRAM,
`an SRAM,andan internal RAM of a microprocessor. It is
`preferable that the volatile memory 203 has a faster data
`access rate than the non-volatile memory 201 since the
`program is retrieved from the volatile memory 203 rather
`than the non-volatile memory 201. As to the microprocessor
`205, any conventional general purpose, single-chip or multi-
`chip processor, may be utilized as mentioned above.
`This embodiment of the present
`invention provides a
`memory system storing data and/or programs in the non-
`volatile 201 in a compressed form and using the data and/or
`programsafter the microprocessor 205 decompresses them
`by executing the decompression program 211. The memory
`system may store a compression program in the non-volatile
`memory 201. The microprocessor 205 executes the com-
`pression program when data and/or program of the non-
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`volatile memory 201 has been modified and needs to be
`persistently stored.
`Although the above described embodiments use the
`decompression and/or compression algorithm in a form of a
`program, such algorithms may be implemented in an inte-
`grated circuit. Advantageously,
`the integrated circuit for
`decompressing compressed digital information and/or com-
`pressing uncompressed digital information is the micropro-
`cessor 205.
`
`Although the present invention has been described in
`terms of embodiments, other embodiments will become
`apparent to those of ordinary skill in the art, in view of the
`disclosure herein. Accordingly, the present invention is not
`intended to be limited by the recitation of the embodiments,
`but is instead intended to be defined solely by reference to
`the appended claims.
`What is claimedis:
`1. A device controller for controlling operation of a
`peripheral device connected to a host computer, the control-
`ler comprising:
`a volatile memory;
`a non-volatile memory storing a compressed program;
`and
`
`a microprocessor in data communication with the volatile
`memory and the non-volatile memory for executing
`programs, wherein the microprocessor decompresses
`the compressed program and stores the decompressed
`program into the volatile memory for execution and
`wherein the device controller connects the peripheral
`device to the host computer, and the compressed pro-
`gram comprises a device operating program for con-
`trolling operation of the peripheral device.
`2. The controller as defined in claim 1, wherein the
`volatile memory has a faster data access rate than the
`non-volatile memory.
`3. The controller as defined in claim 1,
`volatile memory comprises a DRAM.
`4. The controller as defined in claim 1,
`non-volatile memory comprises a writable
`memory.
`5. The controller as defined in claim 4, wherein the
`writable non-volatile memory comprises a flash memory.
`6. The controller as defined in claim 4, wherein the
`compressed program stored in the non-volatile memory can
`be updated by overwriting the compressed program with a
`new compressed program received from the host computer
`connected to the controller.
`
`wherein the
`non-volatile
`
`wherein the
`
`7, The controller as defined in claim 6, wherein the new
`program is compressed at
`the host computer,
`the new
`compressed program is temporarily stored in the volatile
`memory until being written to the non-volatile memory.
`8. The controller as defined in claim 6, wherein the
`non-volatile memory further stores a compression program
`for compressing digital information in an uncompressed
`form so that the microprocessor can execute the compres-
`sion program without decompression, and wherein the
`microprocessor executes the compression program to com-
`press the new program and stores the new compressed
`program into the non-volatile memory.
`9. The controller as defined in claim 6, further comprising
`an integrated circuit for compressing digital information,
`wherein the integrated circuit compresses the new program
`and stores the new compressed program into the non-volatile
`memory.
`10. The controller as defined in claim 9, wherein the
`integrated circuit comprises the microprocessor.
`
`8
`11. The controller as defined in claim 1, wherein the
`non-volatile memory further stores a decompression pro-
`gram for decompressing compressed digital information in
`an uncompressed form so that
`the microprocessor can
`execute the decompression program without decompression,
`and the microprocessor executes the decompression pro-
`gram to decompress the compressed device operating pro-
`gram and to store the decompressed program into the
`volatile memory when the controller is powered up orreset.
`12. The controller as defined in claim 11, wherein the
`microprocessor executes the device operating program when
`the decompression is completed.
`13. The controller as defined in claim 1, wherein the
`microprocessor executes the device operating program when
`the controller receives a command for operation of the
`peripheral device from the host computer.
`14. The controller as defined in claim 1, wherein the
`peripheral device is a data storage drive.
`15. The controller as defined in claim 14, wherein the data
`storage device is DAT drive.
`16. The controller as defined in claim 10, wherein the
`non-volatile memory comprises a writable non-volatile
`memory, and wherein the decompression program in the
`non-volatile memory can be updated by overwriting the
`decompression program with a new decompression program
`received from a host computer connected to the controller.
`17. The controller as defined in claim 1, wherein the
`non-volatile memory comprises an internal RAM of the
`microprocessor.
`18. The controller as defined in claim 1, wherein the
`volatile memory comprises an internal ROM ofthe micro-
`processor.
`19. The controller as defined in claim 1, further compris-
`ing an integrated circuit for decompressing compressed
`digital information, wherein the integrated circuit decom-
`presses the compressed device operating program and stores
`the decompressed program into the volatile memory when
`the controller is powered up orreset.
`20. A method for executing a compressed program in a
`device controller for controlling a peripheral device con-
`nected to a host computer through the controller, the method
`comprising:
`checking automatically if a compressed device operating
`program is available in a non-volatile memory of the
`device controller when the controller is powered up or
`reset;
`executing an uncompressed decompression program
`stored in the non-volatile memory to decompress the
`compressed device operating program when the com-
`pressed device operating program is available and
`storing a decompressed device operating program into
`a volatile memory of the device controller; and
`executing the decompressed device operating program to
`control the peripheral device.
`21. The method as defined in claim 20, wherein the
`peripheral device is a data storage drive.
`22. The method as defined in claim 21, wherein the data
`storage drive is a DATdrive.
`23. The method as defined in claim 21, wherein the
`compressed program is a device operating program for
`controlling operation of the peripheral device.
`24. The method as defined in claim 21, wherein the
`non-volatile memory is a writable non-volatile memory.
`25. The method as defined in claim 24, wherein if the
`compressed program is not available in the non-volatile
`memory the controller receives a compressed program from
`the host computer before executing the decompression pro-
`gram.
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`26. The method as defined in claim 25, wherein the
`microprocessor temporarily stores the compressed program
`in the volatile memory while the controller receives the
`compressed program, and the microprocessor transfers the
`compressed program into the non-volatile memory whenthe
`controller completes receiving the compressed program.
`27. A memory system for a peripheral device of a host
`computer, the memory system comprising:
`a volatile memory;
`a non-volatile memory comprising a first section storing
`compressed digital information and a second section
`storing an uncompressed decompression program for
`decompressing the compressed digital information; and
`a microprocessor in data communication with the volatile
`memory and the non-volatile memory for executing
`programs, wherein the microprocessoris configured to
`decompress the compressed digital information to sto