Avago Technologies LSI53C1020 - Manual (Page 52)

2-26 Functional Description
Version 2.4 Copyright © 2001–2004 by LSI Logic Corporation. All rights reserved.
2.5.2 NVSRAM Interface
The LSI53C1020 Fusion-MPT firmware is capable of maintaining an
Integrated Mirroring (IM) volume of the boot drive. IM firmware requires
a 32 Kbyte NVSRAM in order to perform write journaling. Write journaling
is used to verify that the mirrored disks in the IM volume are
synchronized with each other. The NVSRAM also stores additional code
and data used for error and exception handling, and it stores IM
configuration information during serial EEPROM updates. The disk write
log uses approximately 4 Kbytes of the NVSRAM.
Figure 2.5 provides a block diagram illustrating how to connect the
NVSRAM. This design employs the CPLD to latch the address instead
of using separate address latches.
Figure 2.5 NVSRAM Diagram
Table 2.4 Flash Signature Value
Flash Address Flash Signature Values
Bytes [3:0] 0xEA XX XX XX
Bytes [7:4] 0x5A 0xEA 0xA5 0x5A
Bytes [11:8] 0xA5 0x5A 0xEA 0xA5
Bytes [15:12] 0x5A 0xA5 0x5A 0xEA
FLSHALE[1:0]/
MAD[7:0]
MAS[1:0]
MAD[7:0]
MAD[14:0] A[14:0]
D[7:0]
RAMCE/
RAMOE/
RAMWE[0]/
CE/
OE/
WE/
NVSRAM (32 K x 8)
3.3 V
CPLD
CY37032