m29w400d Numonyx, m29w400d Datasheet - Page 17

• Manufacturer Part Number: m29w400d
• Description: 4 Mbit 512 Kb X 8 Or 256 Kb X 16, Boot Block 3 V Supply Flash Memory
• Manufacturer: Numonyx

M29W400DT, M29W400DB
3.6
3.7
3.8
Special bus operations
Additional bus operations can be performed to read the electronic signature and also to
apply and remove block protection. These bus operations are intended for use by
programming equipment and are not usually used in applications. They require V
applied to some pins.
Electronic signature
The memory has two codes, the manufacturer code and the device code, that can be read
to identify the memory. These codes can be read by applying the signals listed in
and
Block protection and blocks unprotection
Each block can be separately protected against accidental Program or Erase. Protected
blocks can be unprotected to allow data to be changed.
There are two methods available for protecting and unprotecting the blocks, one for use on
programming equipment and the other for in-system use. Block Protect and Chip Unprotect
operations are described in
Table 2.
1. X = V
Bus Read
Bus Write
Output Disable
Standby
Read
manufacturer code
Read device code
Table
Operation
IL
or V
3, Bus operations.
IH
Bus operations, BYTE = V
.
V
V
V
V
V
E
X
IH
IL
IL
IL
IL
Appendix B: Block
V
V
V
V
V
G
X
IH
IH
IL
IL
IL
V
V
V
V
V
W
X
IH
IH
IH
IH
IL
IL
Cell address
Command address
X
X
A0 = V
A9 = V
others V
A0 = V
A9 = V
others V
(1)
DQ15A–1, A0-A17
Address inputs
protection.
IL
ID
IH
ID
, A1 = V
IL
IL
,
,
, A1 = V
or V
or V
IH
IH
IL
IL
,
,
DQ14-DQ8
Hi-Z
Hi-Z
Hi-Z
Hi-Z
Hi-Z
Hi-Z
Data inputs/outputs
Bus operations
(M29W400DB)
(M29W400DT)
Data output
Data input
DQ7-DQ0
ID
Hi-Z
Hi-Z
EEh
EFh
Table 2
20h
to be
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