NAND01GR3A datasheet(20/57 Pages) STMICROELECTRONICS

20 / 57 page

NAND128-A, NAND256-A, NAND512-A, NAND01G-A

20/57

DEVICE OPERATIONS

Pointer Operations

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 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 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

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.).

Figure 11. 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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