Thinkpad Low Density Memory Modules

[glgermain]

I'm confused about the type of "low density" 256 mb sodimm modules needed for the 240/X20/T20 computers. I understand the 16chip modules (8 per side) are all low density. But are some of the 8 chip (4 per side) also low density, or are all of the 8 chip high density (and won't work)? For example, the really cheap high density modules are advertised as 16x16. There are more expensive 8 chip modules advertised as 32x8 and 32x 64, and then there are the 16 chip modules which are the most expensive of all. I didn't get a good look at the Samsung 256mb modules that worked in my friends 240 to count the chips, but I think it had only 4 chips per side (not sure though). Any knowledge on the subject would be appreciated.