Memory; Sram; Flash Eprom; Nand Flash - Rabbit RCM3365 User Manual

4.4 Memory

4.4.1 SRAM

RCM3365/RCM3375 boards have 512K of program-execution fast SRAM at U11. The
program-execution SRAM is not battery-backed. There are 512K of battery-backed data
SRAM installed at U10.

4.4.2 Flash EPROM

RCM3365/RCM3375 boards also have 512K of flash EPROM at U9.
NOTE: Rabbit recommends that any customer applications should not be constrained by
the sector size of the flash EPROM since it may be necessary to change the sector size
in the future.
Writing to arbitrary flash memory addresses at run time is also discouraged. Instead, use a
portion of the "user block" area to store persistent data. The functions writeUser-
Block and readUserBlock are provided for this. Refer to the
cessor Designer's Handbook
information.

4.4.3 NAND Flash

The RCM3365 and the RCM3375 support a removable
Web pages. The RCM3365 and the RCM3375 both can handle up to a 128MB removable
, and the RCM3365 model also has a 32MB onboard NAND flash.
xD-Picture Card
NOTE: Rabbit-based systems do not implement the xD-Picture Card™ specification for
data storage, and are neither compatible nor compliant with xD-Picture Card™ card
readers.
The NAND flash and
tions, but are generally unsuitable for direct program execution. The NAND flash differs
from parallel NOR flash (the type of flash memory used to store program code on Rabbit-
based boards and RabbitCore modules currently in production) in two respects. First, the
NAND flash requires error-correcting code (ECC) for reliability. Although NAND flash
manufacturers do guarantee that block 0 will be error-free, most manufacturers guarantee
that a new NAND flash chip will be shipped with a relatively small percentage of errors,
and will not develop more than some maximum number or percentage of errors over its
rated lifetime of up to 100,000 writes. Second, the standard NAND flash addressing
method multiplexes commands, data, and addresses on the same I/O pins, while requiring
that certain control lines must be held stable for the duration of the NAND flash access.
The software function calls provided by Rabbit for the NAND flash take care of the data-
integrity and reliability attributes.
* RCM3365 modules sold before 2008 had 16MB fixed NAND flash memory.
38
and the
Dynamic C Function Reference Manual
are particularly suitable for mass-storage applica-
xD-Picture Card
Rabbit 3000 Micropro-
for additional
to store data and
xD-Picture Card™
RabbitCore RCM3365/RCM3375
*