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510, and OxAA at offset 511. The optimal search string for a GREP expression
will be: “@510\x55\xAA”. Find among all sectors found using the search
criteria precise MBR location (based on the peculiarities of its content).
2. Use internal mode for sector viewing as «Partition Table» and define the
number of expected sectors of Boot sector offset relatively to MBR.
3. Find actual location of the Boot sector relatively to MBR. To do that, move
one sector forward until you find the Boot sector within the expected range of
sectors.
4. Compare actual relative location with the expected one. If these two values are
the same, you can make preliminary conclusion that this task contains no
«mix» condition.
5. FAT table begins a few sectors after the Boot sector (precise value can be
identified by viewing Boot sector as Boot FATxx). In most cases the content
of the table sectors follows a certain principle of increase of the data values in
- those sectors. The pattern can be used as the basis to determine the number of
sectors following each other. 5;
Then you have to identify the number of missing sectors, if any.
Use GREP search or check the most probable offsets to find the missing FAT
sectors. The most probable locations include offsets relative to the address
where the chain of FAT sectors is interrupted, which correspond to the
Interleave Operation specifications supported by the chip. The values include
the offsets of 128 sectors, 256 sectors, 512 sectors. To convert the values into
Pages, page size has to be used in each individual task. First of all, you should
check skipped FAT sectors at those offsets. If a task contains several chips,
checks at corresponding offsets should also be performed in other dumps.
8. Use the collected data and guidelines from the «Main types of «mix»
conditions and methods of their repair» section to determine and perform the
necessary sequence of initial preparation steps.
9. «inversion mix» type can be found and repaired using analysis of sector
content and statistical information about controllers. E.g., if a SMxxxx type
controller has been used in a task, then you can suppose with high probability
that the dump is inverted.
10. «Mix» conditions with a bytewise interleave can be found and repaired using
analysis of sector content. In case of such «mix» type the main structures will
be present in sectors with a byte gap. E.g., the ASCII record «FAT32» in case
of such «mix» type will look like: «FT2». Search for the «A3» combination in
the dump or other chips will be positive at that.
an
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5.11. Interleaved Operation.
Due to the constantly increasing requirements to the speed of manipulations with
data arrays, manufacturers of Flash memory chips began to subdivide the matrix of
cells into planes within a single crystal. The planes at that are configured so that
simultaneous read, write and programming operations are now possible for
selected page of a block belonging to each plane,
Plane od Planet Plane 2 Plane 3
{2048 blocks) (2048 blocs) (2048 blocs) {2048 blocks)
LRO 1 Block 1 Block 4096 Block 4097
Page Tage Paged Pago
1] Page? Paget Page
Pages? Page CCI
[Pages Page 63
[Blocks Block 4098 Block 4099
Page Paseo] Pageo
Page Page Page
Pages Page Page Page &
Page 63 Page 6s Page gs Page 6
Block 4092 Block 4093 Block 8188 Block 8189
Page Pageo Page Paged
Page Page Page t Paget
Page62 Page Page 62 Page 6
Page 63 Page 63 Page 63 Page 63
Block 4094 Block 4095 [Block 8190 Block 8191
Pigeo, Paseo Page Pageo
Paget Paget Paget Page?
Page 62 Page? Page G2 Page ot
Page 65 Page 63 Page 63 Page 63
Process] Essen] [Poe regitera2a byes] Ferse]
Figure 20. Flash chip structure,
To perform those operations, the list of commands supported by NAND-based
Flash memory chips has been supplemented with the Two-Plane group of
commands (generally, N-Plane). They include Two-Plane Page Read, Two-Plane
Page Program, Two-Plane Block Erase.
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