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SmartMedia Technical Notes

Identifying Invalid Block(s)

Invalid Block(s)

Invalid blocks are defined as blocks that contain one or more invalid bits whose reliability is not guaranteed by Samsung. The infor-

mation regarding the invalid block(s) is so called as the invalid block information. An invalid block(s) does not affect the performance

of valid block(s) because it is isolated from the bit line and the common source line by a select transistor. The system design must be

able to mask out the invalid block(s) via address mapping.

SSFDC Forum specifies the logical format and physical format to ensure compatibility of SmartMedia. Samsung pre-formats Smart-

blocks the 6th byte in the spare area (column address 517 for 4MB SmartMedia and higher densities, 261 for 2MB SmartMedia,

respectively) contains two or more "0" bits to indicate a invalid block. Other than the blocks with format data and the invalid blocks

are erased(FFh). Since the invalid block information is also erasable in most cases, it is impossible to recover the information once it

has been erased. Therefore, the system must be able to recognize the invalid block(s) based on the original invalid block information

and create the invalid block table via the following suggested flow chart(Figure 1). Any intentional erasure of the original invalid block

information is prohibited.

*

Check "FFh" at the column address

Figure 1. Flow chart to create invalid block table.

Start

Set Block Address = 0

Check "FFh" ?

Increment Block Address

Last Block ?

End

No

Yes

Yes

Create (or update)

No

Invalid Block(s) Table

517 of the first page in the block