memory for an LX164

[Juhana Helovuo]

Maurice Hilarius wrote:
 >Ted Goodridge, Jr wrote:
 >
 >> You sure 256 sticks will work? My (albiet old copy of) manual shows
 >> max  memory of 512 megs, 4x128 chips.
 >>
 >> I just wnat to be sure before I buy.
 >>
 >
 >
 >256MB modules work.
 >The manual was written before 256MB modules were commonly available.

[I am now replying to a rather ancient thread, but I ran across the same 
problem.]


Maurice is right in the fact that 256MB unbuffered ECC SDRAM DIMMs work 
in a 164LX motherboard. An 164LX data sheet by Samsung lists support for 
256MB DIMMs also.

However, not all 256MB DIMMs work, even if they satisfy the spec above.

For example, Kingston KVR133X72C3/256 (PC133) does NOT work, it is not 
recognized by the motherboard at all. I tested this myself.

On the other hand, Kingston KVR100X72C2/256 (PC100) seems to work fine. 
I tested this myself also.

The Kingston part numbers would lead one to think that the main 
differences between these modules are the maximum supported frequency 
(133 MHz vs. 100 MHz) and minimum CAS latency (3 clocks vs. 2 clocks), 
but since the 164LX uses a frequency less than 100 MHz (66?), and both 
of these modules should reach CL=2 at 100 MHz or less, the differences 
do not seem significant.

The important difference seems to be the internal organization of the 
memory modules. The organization of the DIMMs is visible to the memory 
controller, as it has to generate memory addressing signals according to 
the structure of the DIMMs.

The Kingston PC133 module is built from 9 chips of 256 Mbits each, with 
an internal organization of 32M x 8 bits each. It seems that the 21174 
memory controller on the 164LX board does not support this configuration.

The Kingston PC100 module is built from 18 chips of 128 Mbits each, with 
an internal organization of 16M x 8 bits each. This is supported by the 
21174, although some older docs do not mention it.


I did not successfully test other brands of memory, but I believe they 
should be ok as long as they have a structure similar to the Kingston 
PC100 part mentioned above.


Juhana Helovuo