| 摘要 |
<p>PURPOSE:To control a data area including a defective part of the information recorded into a memory card having an EEPROM. CONSTITUTION:An error bit map is formed in a control area to show the propriety of the storage state of each cluster of a date area in a single bit. The error bit map is held at '1' equal to an initial state as long as the cluster storage state is normal in a cluster verifying state. Meanwhile '0', i.e., the inverted value of the initial state is written in the error bit map if the cluster storage state is abnormal in the cluster verifying state. When '0' is written, no erasure processing is required for an EEPROM. Then the control area can be rewritten just by writing '0' over the state of '1'. In an erasure state, the error bit map is once reed out of a system memory and then returned to a prescribed position of the control, area after erasion. As a result, a defective cluster is never used after erasure and the data can surely be stored.</p> |
