Management process for abacus type memory card e.g. EEPROM - uses writing to data cells of neighbouring row of memory before data in memory row is erased

摘要

The process involves erasing cells in a given row by performing a double write initially on a cell of the immediately following row (2,3). For each double write operation a second cell on the same row as the double write is written to (4). The starting row is inverted, erasing it (3). The preceding row is then inverted (5) and a cell in the starting row written to (6). If a row has an odd number of filled cells, a write is performed in a supplementary cell in this row (7). If when a card is read any row is found to have an odd number of filled cells, an error is signalled. ADVANTAGE - Improved reliability in revising balance of prepayment on EEPROM memory card.