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Hello!
I have tp-link mr3220 with gargoyle [shrinked openwrt], and to many plugins 
extroot cant survive my wife hard resets....
I can solder SMD, so i think about RAM mod,
do You know if it's posible like in MR3420 [ 16M Flash and 64M RAM ] ?
What kind of memory can I use ?
Best regards!
(Last edited by sosw on 25 Sep 2012, 20:32)
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yes, of course: http://wiki.openwrt.org/ru/toh/tp-link
most of the SO-DIMM DDR1 333-400MHz 512MB double sided 8-chip or 256MB single sided 4-chip laptop modules are ok for the mod, but its better to check the datasheet of the RAM chip (not the module's manual!) first... you should find that in pdf its organization is 32Mx16bit, and then you will find 16 databus lanes in its package pinout section! router board drives it on 400MHz, but i found that in most DDR333 chip's doc it runs on 333MHz in CL2.5 and runs on 400MHz in CL3 latency mode > it should be ok for the router...
further modification of uboot or firmware is not necessary if you dont swap the flash IC too...
easiest way to remove chips from both SODIMM module and router board is a cheap hot air gun (mine was ~15$) :
first, i removed the 2 electrolyt caps next to the RAM chip on my TL-MR3220, then i covered the heatsink and other bigger parts around the RAM chip with some layer of tin foil. dont mess with small SMD parts around, they should survive it! and the hot "wind" might push them away with tin foil like a sail canvas - so its better to keep them clean... 
switch the gun to high mode, then do circles with it around the chip and try to lift the edge of the chip gently with a blade...
then clean the traces and pins with a soldering iron and desoldering wire, then solder the 64MB chip with iron to its place back
but first, its better to do some exercise on a worthless old memory module...
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