Electrical computers and digital processing systems: support – Reconfiguration
Reexamination Certificate
1999-02-10
2002-05-21
Butler, Dennis M. (Department: 2182)
Electrical computers and digital processing systems: support
Reconfiguration
Reexamination Certificate
active
06393561
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a recorded information reproducing apparatus which uses a medium such as CD-ROM (Compact Disk-Read Only Memory), DVD (Digital Versatile Disk, Digital Video Disk), DVD-ROM, DVD-RAM, CDI (Compact Disk-Interactive), DVI (Digital Video Interactive) or MOD (Magneto Optical Disk), an information recording/reproducing apparatus including such recorded information reproducing apparatus, and a disk drive which is a generic term for those apparatus, as well as a computer in which such disk drive is mounted, and also relates to an art which facilitates rewriting of a program for controlling a recorded information reproducing operation or the like of, for example, a CD-ROM drive mounted in a personal computer as standard equipment, and which is useful for applications to improve the reliability of rewriting.
BACKGROUND ART
Disk drives such as CD-ROM drives have rapidly spread as recorded information reproducing apparatus to be interfaced with personal computers, game machines or the like. Because such CD-ROM drives or the like are based on standards for audio CD players, their data transfer speeds and data access speeds require to be increased, as compared with the audio CD players. In addition, as opposed to the audio CD players which can use processing such as interpolation of data or holding of previous values if data error cannot be corrected, such processing is meaningless to data for personal computers and it is necessary to increase the data error correcting capabilities of the CD-ROM drives.
To increase data access speed, such a CD-ROM drive or the like has adopted the art of reading and reproducing-recorded information while rotating a CD-ROM disk at a speed, for example, twice or four times as fast as its normal speed, as by raising the frequency band of a preamplifier for amplifying information read from the disk, reinforcing a pickup servo circuit, or increasing the operational speed of a digital signal processing circuit. Furthermore, the art of adding a quadruple error-correcting code to a double error-correcting code has been implemented to improve the error correcting capability of such a CD-ROM drive.
However, today, the fact is that the speed of reproduction of recorded information is being changed to a far faster speed within a short period, as represented by CD-ROM drives. In the past, the reproducing speed was changed from standard speed (the linear velocity of an audio CD during reproduction) to double speed and then from double speed to quadruple speed, in a cycle of two or more years, but today, the reproducing speed is being rapidly changed from sextuple speed to octuple speed or more in a cycle of several months.
In such a situation, each time the reproducing speed is increased, the manner of circuit control, circuit constants or the like must be changed in a short period so as to change the frequency band or the gain of the preamplifier, to reinforce the pickup servo circuit, to increase the operational speed of the digital signal processing circuit, to optimize error-correcting processing, and so on.
If microcomputers are to be used for recorded information reproduction control in CD-ROM drives or the like, their recorded information reproduction control programs (including constant tables) must be changed. If such a program is to be provided in the form of a mask ROM, a mask pattern cannot be changed without a delay in the above-described extremely short cycle of change in the reproducing speed, i.e., an extremely short product cycle.
Japanese Patent Laid-Open No. 6-187141 discloses an arrangement in which a processing program for reproducing recorded information from a disk or recording information on a disk in a magneto optical disk drive is stored in a rewritable ROM to facilitate the bug-fixation or upgrading of the processing program.
Specifically, the magneto optical disk drive includes a SCSI (Small Computer System Interface) controller connected to a host and a driver connected to this controller, and firmware (processing program) for the controller is stored in a rewritable ROM and firmware for the driver is stored in an EEPROM (Electrically Erasable and Programmable ROM). If the firmware for the controller is to be rewritten, the host transfers the firmware for the controller to a buffer memory in the controller, and also transfers a write program stored in the ROM in the controller to a RAM in the controller, and then issues a command to the controller. When receiving the command, the controller writes the contents of the ROM with the firmware for the controller stored in the buffer memory, in accordance with the rewrite program held in the RAM. At the same time as this rewriting, the write program stored in the ROM is also updated. If the firmware for the driver is to be rewritten, the host transfers a rewrite program for the driver to the RAM of the controller via the buffer memory, and also transfers the firmware for the driver to the buffer memory of the controller. Then, a CPU of the controller is made to execute the rewrite program stored in the RAM. The CPU of the controller sets the firmware for the driver and addresses in the RAM of the driver in accordance with the rewrite program, and then issues a command to the CPU of the driver. The driver has a mask ROM which supports communication and basic commands, and the CPU of the driver which has received the command executes the program of the mask ROM and rewrites the contents of the EEPROM with the firmware for the driver stored in the RAM.
However, in the above-described arrangement which updates the rewrite program stored in the ROM, together with the firmware for the controller during the rewriting-of the firmware for the controller, if an abnormality occurs and the rewrite program in the RAM is broken during the rewriting of the ROM, it is expected that it takes time to recover the controller to the normal state.
In the arrangement in which a rewrite control program for the EEPROM and an interface program for rewriting are stored in the mask ROM separate from the EEPROM which holds the firmware for the driver, the mask ROM is needed in addition to the EEPROM, so that the physical scale of a system is increased. In addition, although the mask ROM is externally attached to a microcomputer or a microprocessor which is a semiconductor integrated circuit, the amount of logic required for chip select control and the like over the externally attached memory increases, and in this respect as well, it is expected that the physical scale of the disk drive increases.
In the above-described prior art, the firmware for the driver and the firmware for the controller are separately stored in the rewritable ROM and the EEPROM. The firmware for the driver is a control program which corresponds to the characteristics of a servo control circuit and the like included in the driver. The firmware for the controller is a control program for realizing interface specifications which correspond to the host. The reason why the processing programs for the magneto optical disk drive are separately stored in the rewritable ROM and the EEPROM is that the control program for the controller can be executed in conformity to interface specifications convenient for a driver adjusting operation during the manufacture of the magneto optical disk drive, and after the control program for the driver is set, the control program for the controller can finally be rewritten according to interface specifications intended for the desired host. This is intended to simplify adjustment operation and product control for the magneto optical disk drive. However, the present inventor has made it apparent that in the arrangement in which the control program for the controller and that for the driver are separately stored in the ROM and the EEPROM, the sequence of rewriting of the control program is complicated and it takes time to rewrite the control program.
The rewrite program for the ROM of the controller is held in the ROM itself, and the rewrite program for the EEPROM of the driver is he
Hagiwara Mitsuo
Ishii Tsutomu
Shibasaki Nobuo
Takahashi Hiromasa
Yamato Satoshi
Butler Dennis M.
Hitachi , Ltd.
Mattingly Stanger & Malur, P.C.
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