andrew;
>it faster than ~20-50KHz.  Should be no problem for SDRAM or similar, or
>even directly to magnetic media.  Any info on this anywhere?  The PICLIST

the datasheets for the sdram chips is a good place to start. i strongly suggest you get more than
one manufacturer's datasheet - you can use one to decipher the obscure sections of the other. iirc
hitachi's datasheets were quite readable. don't get put off by the state diagram - you'll probably
only need a tiny subset of those states! use auto precharge mode to make refreshing a lot easier,
then just chuck in a refresh command now and again.
http://www.hitachi-eu.com/hel/ecg/products/memory/struktur/fr_c_d_s.htm

ram modules are then just a handful of these devices (usually 8 bit wide rams, sometimes 4 bits
wide) wired up to give a wide data bus, with a little serial eprom on board to tell you what they
are:
http://www.micron.com/products/datasheets/modds.html#144pin%20DIMM

...looks like sodimms have just as wide a data bus as ordinary dimms btw, pity as it might have been
handy. this probably means you be running the sdrams with a burst length of 1 to avoid too much
external logic.

finding a neat way to wire the whole lot up will be an interesting task.


if you do head down the sdram route and run into difficulties then i may be able to help - i have a
reasonable amount of experience with controlling sdram.

Regards,
Simon

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