It seems that large serial RAM (e.g. 32kBytes RAM) is a product that nobody
offers (why?) but many people ask for in forums e.g. read here a similar
question: http://wearables.blu.org/wear-hard-02/20028065.html

Maybe the FRAMS (ramtron.com) are a better choice than the Atmel parts;
but still overkill. There are many cases we do not need permanent storage, but 
unlimited read write access. 

10^10 read/write cycles for the FRAM's sounds much; but if I write to
a single cell at maximum bus speed I only need 3 days to destroy the chip
(hope I calculated right :-).

Seems to be a market niche nobody has discovered yet. Many small
microprocessors today have large Flash (>64kBytes) but often not more than
2kBytes RAM (much RAM makes the chip expensive). But you have serial busses
SPI or I2C with up to 1(10)MBit/s -> 100kBytes/s (1MB/s) (with serial auto
increment read/write) -> 10(1)us access time - fast enough for many
applications. (e.g. data acquisition that needs some scratch ram for the
pre-trigger, or you want to draw a graphic for a small dot matrix printer;
your application could use a cheap 8 pin processor with 2kFlash but you need
32k RAM). A single SO8 oder SOT23-5 would be much smaller as a big controller
with many pins and a parallel SRAM or the PLD/RAM combination suggested here
(PLD's are not known to be power saving parts ;-(

Conclusions as long as microcontrollers does not come with 64kRAM on chip
a serial RAM of this size makes sense.

M.
-- 
Author: Matthias Weingart
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