m29w400b-100za6tr STMicroelectronics, m29w400b-100za6tr Datasheet - Page 36

• Manufacturer Part Number: m29w400b-100za6tr
• Description: 64 Mbit 8mb X8 Or 4mb X16, Multiple Bank, Boot Block 3v Supply Flash Memory
• Manufacturer: STMicroelectronics

Dual operations and multiple bank architecture
6
The Multiple Bank Architecture of the M29DW640F gives greater flexibility for software developers to split
the code and data spaces within the memory array. The Dual Operations feature simplifies 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 operations. 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 programming and other banks in read mode.
By using a combination of these features, read operations are possible at any moment in the device.
Table 10
only the commonly used commands are represented in these tables.
Table 10.
1. If several banks are involved in a program or erase operation, then only the banks that are not concerned with the operation
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 a Program Resume is allowed if the bank was previously in Program Suspend mode.
6. Only an Erase Resume is allowed if the bank was previously in Erase Suspend mode.
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Idle
Programming
Erasing
Program Suspended
Erase Suspended
Status of bank
are available for dual operations.
and
Dual operations and multiple bank architecture
Dual operations allowed in other banks
Table 11
(1)
show the dual operations possible in other banks and in the same bank. Note that
Array
Read
Yes
Yes
Yes
Yes
Yes
Register
Status
Yes
Read
No
No
No
No
(3)
(2)
Commands allowed in another bank
Query
Read
CFI
Yes
Yes
Yes
No
No
Select
Auto
Yes
Yes
Yes
No
No
Program
Yes
Yes
No
–
–
Erase
Yes
No
No
–
–
(1)
Program/
Suspend
Erase
Yes
No
No
–
–
(3)
M29DW640F
Program/
Resume
Erase
Yes
Yes
Yes
No
No
(4)
(5)
(6)