Error detection/correction and fault detection/recovery – Data processing system error or fault handling – Reliability and availability
Reexamination Certificate
1998-03-16
2001-01-09
Hua, Ly V. (Department: 2785)
Error detection/correction and fault detection/recovery
Data processing system error or fault handling
Reliability and availability
C714S006130, C713S001000
Reexamination Certificate
active
06173412
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of Invention
The invention relates to an apparatus and method for initializing a writeable and nonvolatile memory device. More particularly, the invention relates to initializing a writeable and nonvolatile memory device by storing an operation setting value stored in a ROM when powered is applied.
2. Description of Related Art
Many electronic devices, such as printers or facsimiles, are equipped with writeable and nonvolatile memories. In a device in which operation setting values are stored in a writeable and nonvolatile memory, for example, an EEPROM, initial values stored in the ROM are also stored in the EEPROM before shipment.
After being shipped, such electronic devices may experience a situation where the ROMs need to be replaced with ROMs storing different contents due to debugging of control programs or changes in the specification, for example. The replacement of ROMs is normally performed by servicepersons, at service centers, office computer technicians, or the like. Since initial values of a new ROM have been changed, it is necessary to write the initial values into the EEPROM when the new ROM is installed.
This rewriting operation is normally performed manually by servicepersons. However, servicepersons may make mistakes. If a serviceperson fails to properly rewrite initial values, the electronic device becomes unable to operate properly. Reliability problems thus arise.
If a serviceperson replacing a ROM is uninformed that the contents of the replacement ROM have been altered, the serviceperson would not perform the initial value rewriting operation. That is, the serviceperson would not store the initial values stored in the new ROM into the EEPROM.
SUMMARY OF THE INVENTION
Accordingly, an electronic apparatus is provided having a writeable and nonvolatile memory device which may not need a person to perform a memory rewriting operation, even when a ROM is replaced. A method for initializing the memory device is also provided.
The writeable
onvolatile memory-equipped electronic apparatus may include a ROM provided in a data processing device, and a writeable and nonvolatile memory device that stores an operation setting value. A determination device is also provided which, when powered on, determines whether there is a change in the storage contents of the ROM. When the determination device determines that there is a change in the storage content of the ROM, a first writing device initializes the memory device by writing the initial value stored in the ROM into the memory device.
When powered on, the determination device may also compare a checksum value stored in the ROM and a value stored in a predetermined area in the memory device. If the checksum value differs from the value stored in the predetermined area, the determination device determines that the ROM has been changed.
When powered on, the determination device may also determine whether the ROM has been changed by comparing a value stored in one high order byte of the checksum stored in the ROM and a value stored in one byte in the predetermined area of the writeable and nonvolatile memory device.
The electronic apparatus may further include a second writing device, separate from the first writing device, that writes into the memory device a value to be used in order to determine whether there is a change in the storage content of the ROM. The second writing device may write into the memory device after the memory device is initialized by the first writing device.
The electronic apparatus may also have the following structure. The checksum stored in the ROM may be provided in a two-byte storage area, and the value stored in the predetermined area of the memory device is provided in a two-byte storage area. A high/low comparison device may be provided which compares the checksum value stored in the high order byte and the checksum value stored in the low order byte of the two-byte storage area of the ROM in order to determine whether there is a change in the storage content of the ROM.
If the high/low comparison device determines that the value stored in the high order byte of the checksum differs from the value stored in the low order byte of the checksum, a second determination device may be provided which determines whether the ROM has been replaced by comparing the value stored in the low order byte of the checksum and a value stored in the low order byte of the two-byte storage area of the predetermined area in the memory device. However, if the high/low comparison device determines that the value stored in the high order byte of the checksum equals the value stored in the low order byte of the checksum, the second determination device compares a value obtained by adding a predetermined value to the value stored in the low order byte of the checksum and the value stored in the low order byte of the two-byte storage area of the predetermined area in the memory device.
The electronic apparatus may also be structured as follows. In a situation where the second determining device determines that the ROM has been replaced, because the high/low comparison device has determined that the value stored in the high order byte of the checksum of the ROM differs from the value stored in the low order byte of the checksum, the high/low comparison device determines that the second writing device may write the value stored in the low order byte of the checksum of the ROM into the low order byte of the predetermined two-byte storage area in the memory device. However, if the high/low comparison device has determined that the value stored in the high order byte of the checksum of the ROM equals the value stored in the low order byte of the checksum, the second writing device may write the value obtained by adding the predetermined value to the value stored in the low order byte of the checksum of the ROM into the low order byte of the predetermined two-byte storage area in the memory device. The predetermined value to be added may be 1.
An initializing method may also be provided to be performed on a writeable and nonvolatile memory device when the electronic apparatus is powered on. The method may include the following steps. In one step, a checksum storage area is provided in a ROM for storing a checksum. In another step, a checking storage area is provided in a predetermined area in a writeable and nonvolatile memory device. In a first comparing step, a value stored in the checksum storage area in the ROM is compared with a value stored in the checking storage area in the memory device. If it is determined in the first comparing step that the value stored in the checksum storage area differs from the value stored in the checking storage area, the memory device is initialized in an initializing step. In a writing step, the value stored in the checksum storage area in the ROM is written into the checking storage area in the memory device.
The method may have further additional steps as follows. Two bytes are provided for the checksum storage area in the ROM, and two bytes are provided for the checking storage area in the predetermined area in the writeable and nonvolatile memory device. In a first comparing step, a value stored in one high order byte of the checksum storage area in the ROM is compared with a value stored in one high order byte of the predetermined area in the memory device. In an initializing step, the memory device is initialized if it is determined in the first comparing step that the value stored in the high order byte of the checksum storage area differs from the value stored in the high order byte of the checking storage area. In a writing step, the value stored in the high order byte of the checksum storage area in the ROM and a value stored in the low order byte of the checksum storage area are written into the memory device.
The method may have further steps as follows. If it is determined in the comparing step that the values are equal, it is then determined in a high/low determining step whether the value stored in the high order byte of the checksu
Hatamura Junji
Isozaki Atsushi
Brother Kogyo Kabushiki Kaisha
Hua Ly V.
Oliff & Berridg,e PLC
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