NAND128-A, NAND256-A, NAND512-A, NAND01G-A
DEVICE OPERATIONS
Pointer Operations
second half of the main area) that is Bytes 256
to 511.
As the NAND Flash memories contain two differ-
ent areas for x16 devices and three different areas
for x8 devices (see Figure 11.) the read command
codes (00h, 01h, 50h) are used to act as pointers
to the different areas of the memory array (they se-
lect the most significant column address).
The Read A and Read B commands act as point-
ers to the main memory area. Their use depends
on the bus width of the device.
In both the x8 and x16 devices the Read C com-
mand (50h), acts as a pointer to Area C (the spare
memory area) that is Bytes 512 to 527 or Words
256 to 263.
Once the Read A and Read C commands have
been issued the pointer remains in the respective
areas until another pointer code is issued. Howev-
er, the Read B command is effective for only one
operation, once an operation has been executed
in Area B the pointer returns automatically to Area
A.
■
In x16 devices the Read A command (00h)
sets the pointer to Area A (the whole of the
main area) that is Words 0 to 255.
The pointer operations can also be used before a
program operation, that is the appropriate code
(00h, 01h or 50h) can be issued before the pro-
gram command 80h is issued (see Figure 12.).
■
In x8 devices the Read A command (00h) sets
the pointer to Area A (the first half of the main
area) that is Bytes 0 to 255, and the Read B
command (01h) sets the pointer to Area B (the
Figure 11. Pointer Operations
x8 Devices
x16 Devices
Area A
(00h)
Area B
(01h)
Area C
(50h)
Area A
(00h)
Area C
(50h)
Bytes 512
-527
Words 256
-263
Bytes 0- 255
Bytes 256-511
Words 0- 255
A
B
C
Page Buffer
A
C
Page Buffer
Pointer
(00h,01h,50h)
Pointer
(00h,50h)
AI07592
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STMICROELECTRONICS [ ST ]
