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The Copy-Back program is configured to quickly and efficiently rewrite data stored in one page without utilizing an external memory. Since the time-consuming cycles of serial access and re-loading cycles are removed, the system performance is improved. The ben- efit is especially obvious when a portion of a block is updated and the rest of the block also need to be copied to the newly assigned free block. The operation for performing a copy-back program is a sequential execution of page-read without serial access and copy- ing-program with the address of destination page. A read operation with "35h" command and the address of the source page moves the whole 2,112-byte data into the internal data buffer. As soon as the device returns to Ready state, Page-Copy Data-input com- mand (85h) with the address cycles of destination page followed may be written. The Program Confirm command (10h) is required to actually begin the programming operation. During tPROG, the device executes EDC of itself. Once the program process starts, the Read Status Register command (70h) or Read EDC Status command (7Bh) may be entered to read the status register. The system controller can detect the completion of a program cycle by monitoring the R/B output, or the Status bit(l/0 6) of the Status Register. When the Copy-Back Program is complete, the Write Status Bit(l/0 0) and EDC Status Bits (110 1 ~ 110 4) may be checked(Figure 10 & Figure 11& Figure 12). The internal write verification detects only errors for "1"s that are not successfully programmed to "O"s and the internal EDC checks whether there is only l-bit error for each 528-byte plane of the source page. More than 2-bit error detection is not available for each 528-byte plane. The command register remains in Read Status command mode or Read EDC Status com- mand mode until another valid command is written to the command register. During copy-back program, data modification is possible using random data input command (85h) as shown in Figurell. But EDC status Bits are not available during copy back for some bits or bytes modified by Random Data Input operation. However, in case of the 528 byte plane unit modification, EDC status bits are abailable.