what does CL2 c lass mean related to memory upgrades

[beanodino1]

pc/ 98'dell dimension L400c desktop 512mb {max memory} 2- mem.slots - present slots/ 1-256mb+ 1-64mb memory.  i was wanting purchase another micron 256mb memory from a seller on ebay & the seller memory spec. listings matched my micron ,but the CL2  part!??  what does" CL2" term or meaning in relation to a memroy upgrade??  could these 2 closely matched microns memory's upgrade be compaditible other than one having  CL2??  thanks!

[Dusty]

Welcome to the CH forums.

CL = CAS Latency.
 
CAS = Column Access Strobe

LATENCY = In a computer system, latency is often used to mean any delay or waiting that increases real or perceived response time beyond the response time desired. Specific contributors to computer latency include mismatches in data speed between the microprocessor and input/output devices and inadequate data buffers.
 
Memory is basically a matrix of capacitors set up in a set of columns and rows. (Think of it as a big spreadsheet.)
 
The memory is accessed first by the column and then the row.  When dealing with CL2 and CL3, the column is accessed and then the row.  When the memory is looking for additional information that is not contained in that row it has to start the process all over again.  This is where the CL part comes in.  With a CL2 there is a delay for the strobe to complete.  So under regular operation it would be 1 regular access cycle + the CL penalty.  That would be 3 cycles for CL2 and 4 cycles for CL3 in order to prepare data for output. (For DDR it is a little different but basically the same.  DDR SDRAM uses clock forwarding and thus is faster than SDR SDRAM)
 
Keep in mind that this is only one latency timing.  There are a bunch of others.
 
For all intents and purposes, CL2 is CAS2 RAM.  The proper terminology is CL. (CAS Latency)
 
CL2 is one half clock cycle faster than CL2.5 and one full clock cycle faster than CL3.  It is faster because the delay is shorter.

Good luck