Registers – Systems controlled by data bearing records – Credit or identification card systems
Patent
1987-01-07
1989-06-20
Envall, Jr., Roy N.
Registers
Systems controlled by data bearing records
Credit or identification card systems
G06K 500
Patent
active
048411310
ABSTRACT:
A portable electronic device having a data memory, constituted by a nonvolatile memory, for storing transaction data, and a central processing unit for performing data-read and data write accessing of the nonvolatile memory. When the CPU writes transaction data in the data memory, it produces a check sum code or an exclusive ORed code of the transaction data, counts the data length of the transaction code including the check sum code or the exclusively ORed code, and appends the check sum code or the exclusively ORed code the data length to the transaction data in order to store it in the data memory. When the CPU reads out the transaction data from the data memory, it produces a check sum code or an exclusive ORed code of the transaction data, counts the data length of the transaction code including the check sum code or the exclusively ORed code, and then compares these values with the check sum code or the exclusively ORed code and the data length read out from the data memory. When a coincidence is found therebetween, the CPU judges that the transaction data written in the data memory is valid.
REFERENCES:
patent: 4564941 (1986-05-01), Woolley et al.
Envall Jr. Roy N.
Kabushiki Kaisha Toshiba
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