The nicest ram I have seen is the Dallas semiconductor RAMport ram,
unfortunatly the largest size is 2k X 8. It requires around 700nS to
read/write - it uses parallel 8 lines to communicate to the memory, but the
clever thing is that it only uses 2 io control lines. The 8 lines of
data/addr bus are fed thru the chip - so you still can use these lines as
io. When you select the ram the output lines are latched, and the ram
accessed.

Geoff.

http://www.dalsemi.com/Prod_info/Memory/ramport.html


>I am considering a data logging project that would sample a number of sensors
>and record the data for later playback into a PC host for analysis. Minimally
>it would need to record one or two hundred bytes per second for several
>minutes, ideally quite a bit more. So something like 32K to 256K of memory
>would need to be written and then later read back. There is almost no
>requirement to randomly access this memory, just need to write it as data
>comes in and read it for upload to the PC.
>
>I know that I could build a data and address bus out of I/O pins, but that
>seems like overkill and would probably use too many pins anyhow.
>
>I have seen serial EEPROMS and they would almost be perfect except for the
>slow programing and power consumption. Is there a serial SRAM available?
>or a simple way to use commodity SRAM chips?

Geoff Smith
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