M28W640 STMicroelectronics, M28W640 Datasheet - Page 39

• Manufacturer Part Number: M28W640
• Description: 64 Mbit 4Mb x16/ Boot Block 3V Supply Flash Memory
• Manufacturer: STMicroelectronics

APPENDIX B. COMMON FLASH INTERFACE (CFI)
The Common Flash Interface is a JEDEC ap-
proved, standardized data structure that can be
read from the Flash memory device. It allows a
system software to query the device to determine
various electrical and timing parameters, density
information and functions supported by the mem-
ory. The system can interface easily with the de-
vice, enabling the software to upgrade itself when
necessary.
When the CFI Query Command (RCFI) is issued
the device enters CFI Query mode and the data
Table 26. Query Structure Overview
Note: Query data are always presented on the lowest order data outputs.
Table 27. CFI Query Identification String
Note: Query data are always presented on the lowest order data outputs (DQ7-DQ0) only. DQ8-DQ15 are ‘0’.
02h-0Fh
Offset
Offset
1Bh
1Ah
00h
10h
27h
00h
01h
10h
12h
13h
14h
15h
16h
17h
18h
19h
11h
P
A
Reserved
CFI Query Identification String
System Interface Information
Device Geometry Definition
Primary Algorithm-specific Extended Query table
Alternate Algorithm-specific Extended Query table
reserved
0020h
8848h
8849h
0051h
0052h
0059h
0003h
0000h
0035h
0000h
0000h
0000h
0000h
0000h
Data
Manufacturer Code
Device Code
Reserved
Query Unique ASCII String "QRY"
Primary Algorithm Command Set and Control Interface ID code 16 bit ID code
defining a specific algorithm
Address for Primary Algorithm extended Query table (see Table 29)
Alternate Vendor Command Set and Control Interface ID Code second vendor -
specified algorithm supported (0000h means none exists)
Address for Alternate Algorithm extended Query table
(0000h means none exists)
Sub-section Name
Description
structure is read from the memory. Tables 26, 27,
28, 29, 30 and 31 show the addresses used to re-
trieve the data.
The CFI data structure also contains a security
area where a 64 bit unique security number is writ-
ten (see Table 31, Security Code area). This area
can be accessed only in Read mode by the final
user. It is impossible to change the security num-
ber after it has been written by ST. Issue a Read
command to return to Read mode.
Reserved for algorithm-specific information
Command set ID and algorithm data offset
Device timing & voltage information
Flash device layout
Additional information specific to the Primary
Algorithm (optional)
Additional information specific to the Alternate
Algorithm (optional)
M28W640CT, M28W640CB
Description
compatible
P = 35h
Bottom
Value
Intel
Top
"Q"
"R"
"Y"
NA
NA
ST
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