Bus operations
M29W800DT, M29W800DB
3.6
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 to be
ID
applied to some pins.
3.6.1
3.6.2
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 Table 2
and Table 3, Bus operations.
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 Appendix C: Block protection.
(1)
Table 2.
Bus operations, BYTE = V
IL
Data inputs/outputs
Address inputs
DQ15A–1, A0-A18
Operation
E
G
W
DQ14-DQ8
DQ7-DQ0
Bus read
VIL
VIL
X
VIL
VIH
VIH
X
VIH Cell address
Hi-Z
Hi-Z
Hi-Z
Hi-Z
Data output
Data input
Hi-Z
Bus write
VIL Command address
Output disable
Standby
VIH
X
X
X
VIH
Hi-Z
A0 = VIL, A1 = VIL, A9 =
VID, others VIL or VIH
Read manufacturer code
Read device code
VIL
VIL
VIL
VIL
VIH
VIH
Hi-Z
Hi-Z
20h
D7h (M29W800DT)
5Bh (M29W800DB)
A0 = VIH, A1 = VIL, A9 =
VID, others VIL or VIH
1. X = VIL or VIH
.
(1)
Table 3.
Bus operations, BYTE = V
IH
Address inputs
A0-A18
Data inputs/outputs
DQ15A–1, DQ14-DQ0
Operation
E
G
W
Bus read
VIL
VIL
X
VIL
VIH
VIH
X
VIH
VIL
VIH
X
Cell address
Data output
Data input
Hi-Z
Bus write
Command address
Output disable
Standby
X
X
VIH
Hi-Z
A0 = VIL, A1 = VIL, A9 = VID,
others VIL or VIH
Read manufacturer code
Read device code
VIL
VIL
VIL
VIL
VIH
VIH
0020h
22D7h (M29W800DT)
225Bh (M29W800DB)
A0 = VIH, A1 = VIL, A9 = VID,
others VIL or VIH
1. X = VIL or VIH
.
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NUMONYX [ NUMONYX B.V ]
