The development of a memory card system for a digital still camera using a 4 Mbit NAND-EEPROM

A card which is compatible with an SRAM memory card and can store a large amount of image data at low cost without battery backup is described. This card incorporates 4-MBit NAND-EEPROMs, a custom designed gate array, and an 8-bit microprocessor. The card utilizes the following techniques: (1) a byte writing method to realize byte writing for header data; (2) an automatic erasing method to reduce apparent writing time; (3) automatic command writing on the NAND-EEPROM, executed within the card without burdening the camera; and (4) a block substitution method for recovering local cell error. These functions can be executed automatically within the card. Accordingly, the present camera system can utilize the card without any limitations caused by the chip architecture of the NAND-EEPROM.<
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