How to identify Chip density by sight?

[vsilly]

Hi folks!
I am trying to understand how to identify whether a RAM DIMM is low-density or high density ram. At this moment I am curious about PC 133 desktop RAM. I have read several definitions about the differences between low-density and high density.

Unfortunately I do not have any RAM modules in front of me to look at and have been trying to find some close-up photos on the Internet with no luck. Maybe this would be clearer to me if I had some examples in front of me.

Here is where I am confused.

According to the explanations I've read, both high-density and low density SDRAM 1GB PC133 have eight chips per side.

Here is the definition I read:

All low density 1GB modules are made with 16 chips (8 chips on each side) using 64Mx8 device.
All high density 1GB modules are made with 16 chips (8 chips on each side) using 128Mx4 device

Given that both the low-density and high density of eight chips on each side, how do you tell when looking at the module whether it is low-density or high-density? Is it written on the chips? Or is it indicated in the labeling of the RAM?

It is important because I plan to make a purchase of a batch of used PC133 and need to know how to tell if what I'm buying in low-density ram. I do not want high-density RAM due to the compatibility issues.

If anyone knows the answer to this or can point me to some information that will explain it thoroughly it would be most appreciated!
Thanks very much!
V

 

[vsilly]

Okay, I have been continuing to mine the Internet and have come up with the following explanation:

"Most High Density PC3200 modules are assembled using Samsung chips. These chips come in both the familiar 22 x 10mm (approx) TSOP2 and smaller squarer 12 x 9mm (approx) FBGA package sizes. High density Samsung chips can be identified by the numbers on each chip. If the sixth and seventh characters are "04" (for example K4H510438D-UCCC) then the chips are x 4 and High Density. If the sixth and seventh characters are "08" then the chips are x 8 and Low Density."

I wish I had some modules in front of me to look at. I wonder if there are other high-density modules that are not Samsung chips? Anyway still interested if anyone has something to add to this explanation that might be enlightening.
Thanks!