NAND512R3A2C datasheet(19/51 Pages) STMICROELECTRONICS

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NAND512-A2C

Device operations

19/51

Device operations

6.1

Pointer operations

As the NAND Flash memories contain two different areas for x16 devices and three different

areas for x8 devices (see Figure 6) the read command codes (00h, 01h, 50h) are used to

act as pointers to the different areas of the memory array (they select the most significant

column address).

The Read A and Read B commands act as pointers to the main memory area. Their use

depends on the bus width of the device.

●

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.

●

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 second half of the main area) that is Bytes 256 to 511.

In both the x8 and x16 devices the Read C command (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. However, 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.

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 program command 80h is issued (see

Figure 7).

Figure 6.

Pointer operations

AI07592

Area A

(00h)

Area B

(01h)

Area C

(50h)

Bytes 0- 255

Bytes 256-511

Bytes 512

-527

Pointer

(00h,01h,50h)

Page Buffer

Area A

(00h)

Area C

(50h)

Words 0- 255

Words 256

-263

Pointer

(00h,50h)

Page Buffer

x8 Devices

x16 Devices

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