256Mb: 3V Embedded Parallel NOR Flash
Dual Operations and Multiple Bank Architecture
Dual Operations and Multiple Bank Architecture
The multiple bank architecture gives greater flexibility for software developers to split
the code and data spaces within the memory array. The dual operations feature simpli-
fies the software management of the device by allowing code to be executed from one
bank while another bank is being programmed or erased.
The dual operations feature means that while programming or erasing in one bank,
read operations are possible in another bank with zero latency.
Only one bank at a time is allowed to be in program or erase mode. However, certain
commands can cross bank boundaries, which means that during an operation only the
banks that are not concerned with the cross bank operation are available for dual oper-
ations. For example, if a Block Erase command is issued to erase blocks in both bank A
and bank B, then only banks C or D are available for read operations while the erase is
being executed.
If a read operation is required in a bank, which is programming or erasing, the program
or erase operation can be suspended.
Also if the suspended operation was erase then a program command can be issued to
another block, so the device can have one block in erase suspend mode, one program-
ming and other banks in read mode.
By using a combination of these features, read operations are possible at any moment.
The tables below show the dual operations possible in other banks and in the same
bank. Note that only the commonly used commands are represented in these tables.
Table 20: Dual Operations Allowed in Other Banks
Commands Allowed in Another Bank
Read
Read
Status
Status of
bank
CFI
Auto
Program/Erase Program/Erase
Read
Yes
Register2
Query
Select Program
Erase
Yes
–
Suspend
Resume
Yes4
No
Idle
Yes3
Yes
No
No
No
Yes
No
No
Yes
Yes
–
Yes3
No
No
–
Programming
Erasing
Yes
No
Yes
No
–
–
No
Program
Yes
No
No
No
No
suspended
Erase
Yes
No
No
Yes
Yes
No
–
Yes5
suspended
1. If several banks are involved in a program or erase operation, then only the banks that
are not concerned with the operation are available for dual operations.
Notes:
2. Read Status Register is not a command. The status register can be read during a block
program or erase operation.
3. Only after a program or erase operation in that bank.
4. Only after a Program or Erase Suspend command in that bank.
5. Only an erase resume is allowed if the bank was previously in erase suspend mode.
PDF: 09005aef84ecabef
m29dw_256g.pdf - Rev. A 10/12 EN
Micron Technology, Inc. reserves the right to change products or specifications without notice.
56
© 2012 Micron Technology, Inc. All rights reserved.
MICRON [ MICRON TECHNOLOGY ]
