| 摘要 |
<p>A data compaction method, for writing data in highly compact binary form in a data storage medium using a microprocessor (30), compresses serially occurring transaction values in a limited memory space by substituting prefix codes for previously occurring values and for commonly occurring previous values. The previous values are listed and updated on tables by the microprocessor (30) so that they are indexed to the prefix codes adaptively to changing local values and changing common values over time. The data compaction method is particularly suitable for an account card having a limited, non-erasable memory used in an automated transaction terminal for maintaining an account record of transactions in frequently recurring amounts. A postage metering terminal (20) is operated by the account card, in which an initial balance has been written and each purchase of postage is recorded. A current balance is recomputed by parsing the previously recorded data. If the current balance is sufficient, the requested value is recorded in compressed form in the card memory (10) and the terminal (20) is operated to print or dispense the requested postage.</p> |
